diff --git a/lib/fluent/plugin/in_tail.rb b/lib/fluent/plugin/in_tail.rb
index fb29dd249f..ef8246f7e8 100644
--- a/lib/fluent/plugin/in_tail.rb
+++ b/lib/fluent/plugin/in_tail.rb
@@ -484,8 +484,8 @@ def close_watcher_handles
     end
 
     # refresh_watchers calls @tails.keys so we don't use stop_watcher -> start_watcher sequence for safety.
-    def update_watcher(target_info, pe)
-      path = target_info.path
+    def update_watcher(tail_watcher, pe, new_inode)
+      path = tail_watcher.path
 
       log.info("detected rotation of #{path}; waiting #{@rotate_wait} seconds")
 
@@ -499,23 +499,26 @@ def update_watcher(target_info, pe)
         end
       end
 
-      rotated_tw = @tails[path]
+      new_target_info = TargetInfo.new(path, new_inode)
 
       if @follow_inodes
-        new_position_entry = @pf[target_info]
+        # When follow_inodes is true, it's not cleaned up by refresh_watcher.
+        # So it should be unwatched here explicitly.
+        tail_watcher.unwatched = true
 
+        new_position_entry = @pf[new_target_info]
+        # If `refresh_watcher` find the new file before, this will not be zero.
+        # In this case, only we have to do is detaching the current tail_watcher.
         if new_position_entry.read_inode == 0
-          # When follow_inodes is true, it's not cleaned up by refresh_watcher.
-          # So it should be unwatched here explicitly.
-          rotated_tw.unwatched = true if rotated_tw
-          @tails[path] = setup_watcher(target_info, new_position_entry)
+          @tails[path] = setup_watcher(new_target_info, new_position_entry)
           @tails[path].on_notify
         end
       else
-        @tails[path] = setup_watcher(target_info, pe)
+        @tails[path] = setup_watcher(new_target_info, pe)
         @tails[path].on_notify
       end
-      detach_watcher_after_rotate_wait(rotated_tw, pe.read_inode) if rotated_tw
+
+      detach_watcher_after_rotate_wait(tail_watcher, pe.read_inode)
     end
 
     # TailWatcher#close is called by another thread at shutdown phase.
@@ -877,18 +880,14 @@ def on_rotate(stat)
               # No need to update a watcher if stat is nil (file not present), because moving to inodes will create
               # new watcher, and old watcher will be closed by stop_watcher in refresh_watchers method
               # don't want to swap state because we need latest read offset in pos file even after rotate_wait
-              if stat
-                target_info = TargetInfo.new(@path, stat.ino)
-                @update_watcher.call(target_info, @pe)
-              end
+              @update_watcher.call(self, @pe, stat.ino) if stat
             else
               # Permit to handle if stat is nil (file not present).
               # If a file is mv-ed and a new file is created during
               # calling `#refresh_watchers`s, and `#refresh_watchers` won't run `#start_watchers`
               # and `#stop_watchers()` for the path because `target_paths_hash`
               # always contains the path.
-              target_info = TargetInfo.new(@path, stat ? stat.ino : nil)
-              @update_watcher.call(target_info, swap_state(@pe))
+              @update_watcher.call(self, swap_state(@pe), stat&.ino)
             end
           else
             @log.info "detected rotation of #{@path}"
diff --git a/test/plugin/test_in_tail.rb b/test/plugin/test_in_tail.rb
index b1e28fc986..81bf0dfa7d 100644
--- a/test/plugin/test_in_tail.rb
+++ b/test/plugin/test_in_tail.rb
@@ -2638,4 +2638,279 @@ def test_lines_collected_with_no_throttling(data)
       end
     end
   end
+
+  sub_test_case "Update watchers for rotation with follow_inodes" do
+    def test_updateTW_before_refreshTW_and_detach_before_refreshTW
+      config = config_element(
+        "ROOT",
+        "",
+        {
+          "path" => "#{@tmp_dir}/tail.txt*",
+          "pos_file" => "#{@tmp_dir}/tail.pos",
+          "tag" => "t1",
+          "format" => "none",
+          "read_from_head" => "true",
+          "follow_inodes" => "true",
+          # In order to detach the old watcher quickly.
+          "rotate_wait" => "1s",
+          # In order to reproduce the same condition stably, ensure that `refresh_watchers` is not
+          # called by a timer.
+          "refresh_interval" => "1h",
+          # stat_watcher often calls `TailWatcher::on_notify` faster than creating a new log file,
+          # so disable it in order to reproduce the same condition stably.
+          "enable_stat_watcher" => "false",
+        }
+      )
+      d = create_driver(config, false)
+
+      tail_watchers = []
+      stub.proxy(d.instance).setup_watcher do |tw|
+        tail_watchers.append(tw)
+        tw
+      end
+
+      Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f| f.puts "file1 log1"}
+
+      d.run(expect_records: 4, timeout: 10) do
+        # Rotate (If the timing is bad, `TailWatcher::on_notify` might be called between mv and new-file-creation)
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f| f.puts "file1 log2"}
+        FileUtils.move("#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt" + "1")
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f| f.puts "file2 log1"}
+
+        # `watch_timer` calls `TailWatcher::on_notify`, and then `update_watcher` updates the TailWatcher:
+        #     TailWatcher(path: "tail.txt", inode: inode_0) => TailWatcher(path: "tail.txt", inode: inode_1)
+        # The old TailWathcer is detached here since `rotate_wait` is just `1s`.
+        sleep 3
+
+        # This reproduces the following situation:
+        #     Rotation => update_watcher => refresh_watchers
+        # This adds a new TailWatcher: TailWatcher(path: "tail.txt1", inode: inode_0)
+        d.instance.refresh_watchers
+
+        # Append to the new current log file.
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f| f.puts "file2 log2"}
+      end
+
+      inode_0 = tail_watchers[0].ino
+      inode_1 = tail_watchers[1].ino
+      record_values = d.events.collect { |event| event[2]["message"] }.sort
+      position_entries = []
+      Fluent::FileWrapper.open("#{@tmp_dir}/tail.pos", "r") do |f|
+        f.readlines(chomp: true).each do |line|
+          values = line.split("\t")
+          position_entries.append([values[0], values[1], values[2].to_i(16)])
+        end
+      end
+
+      assert_equal(
+        {
+          # TODO: This is BUG!! We need to fix it and replace this with the next.
+          record_values: ["file1 log1", "file1 log1", "file1 log2", "file1 log2", "file2 log1", "file2 log2"],
+          # record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
+          tail_watcher_paths: ["#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt1"],
+          tail_watcher_inodes: [inode_0, inode_1, inode_0],
+          tail_watcher_io_handler_opened_statuses: [false, false, false],
+          # TODO: This is BUG!! We need to fix it and replace this with the next.
+          position_entries: [
+            ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+            ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
+            ["#{@tmp_dir}/tail.txt1", "0000000000000016", inode_0],
+          ],
+          # position_entries: [
+          #   ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+          #   ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
+          # ],
+        },
+        {
+          record_values: record_values,
+          tail_watcher_paths: tail_watchers.collect { |tw| tw.path },
+          tail_watcher_inodes: tail_watchers.collect { |tw| tw.ino },
+          tail_watcher_io_handler_opened_statuses: tail_watchers.collect { |tw| tw.instance_variable_get(:@io_handler)&.opened? || false },
+          position_entries: position_entries
+        },
+      )
+    end
+
+    def test_updateTW_before_refreshTW_and_detach_after_refreshTW
+      config = config_element(
+        "ROOT",
+        "",
+        {
+          "path" => "#{@tmp_dir}/tail.txt*",
+          "pos_file" => "#{@tmp_dir}/tail.pos",
+          "tag" => "t1",
+          "format" => "none",
+          "read_from_head" => "true",
+          "follow_inodes" => "true",
+          # In order to detach the old watcher after refresh_watchers.
+          "rotate_wait" => "4s",
+          # In order to reproduce the same condition stably, ensure that `refresh_watchers` is not
+          # called by a timer.
+          "refresh_interval" => "1h",
+          # stat_watcher often calls `TailWatcher::on_notify` faster than creating a new log file,
+          # so disable it in order to reproduce the same condition stably.
+          "enable_stat_watcher" => "false",
+        }
+      )
+      d = create_driver(config, false)
+
+      tail_watchers = []
+      stub.proxy(d.instance).setup_watcher do |tw|
+        tail_watchers.append(tw)
+        tw
+      end
+
+      Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f| f.puts "file1 log1"}
+
+      d.run(expect_records: 4, timeout: 10) do
+        # Rotate (If the timing is bad, `TailWatcher::on_notify` might be called between mv and new-file-creation)
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f| f.puts "file1 log2"}
+        FileUtils.move("#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt" + "1")
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f| f.puts "file2 log1"}
+
+        # `watch_timer` calls `TailWatcher::on_notify`, and then `update_watcher` updates the TailWatcher:
+        #     TailWatcher(path: "tail.txt", inode: inode_0) => TailWatcher(path: "tail.txt", inode: inode_1)
+        sleep 2
+
+        # This reproduces the following situation:
+        #     Rotation => update_watcher => refresh_watchers
+        # This adds a new TailWatcher: TailWatcher(path: "tail.txt1", inode: inode_0)
+        d.instance.refresh_watchers
+
+        # The old TailWathcer is detached here since `rotate_wait` is `4s`.
+        sleep 3
+
+        # Append to the new current log file.
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f| f.puts "file2 log2"}
+      end
+
+      inode_0 = tail_watchers[0].ino
+      inode_1 = tail_watchers[1].ino
+      record_values = d.events.collect { |event| event[2]["message"] }.sort
+      position_entries = []
+      Fluent::FileWrapper.open("#{@tmp_dir}/tail.pos", "r") do |f|
+        f.readlines(chomp: true).each do |line|
+          values = line.split("\t")
+          position_entries.append([values[0], values[1], values[2].to_i(16)])
+        end
+      end
+
+      assert_equal(
+        {
+          record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
+          tail_watcher_paths: ["#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt1"],
+          tail_watcher_inodes: [inode_0, inode_1, inode_0],
+          tail_watcher_io_handler_opened_statuses: [false, false, false],
+          position_entries: [
+            ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+            ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
+          ],
+        },
+        {
+          record_values: record_values,
+          tail_watcher_paths: tail_watchers.collect { |tw| tw.path },
+          tail_watcher_inodes: tail_watchers.collect { |tw| tw.ino },
+          tail_watcher_io_handler_opened_statuses: tail_watchers.collect { |tw| tw.instance_variable_get(:@io_handler)&.opened? || false },
+          position_entries: position_entries
+        },
+      )
+    end
+
+    # The scenario where in_tail wrongly detaches TailWatcher.
+    # This is reported in https://github.com/fluent/fluentd/issues/4190.
+    def test_updateTW_after_refreshTW
+      config = config_element(
+        "ROOT",
+        "",
+        {
+          "path" => "#{@tmp_dir}/tail.txt*",
+          "pos_file" => "#{@tmp_dir}/tail.pos",
+          "tag" => "t1",
+          "format" => "none",
+          "read_from_head" => "true",
+          "follow_inodes" => "true",
+          # In order to detach the old watcher quickly.
+          "rotate_wait" => "1s",
+          # In order to reproduce the same condition stably, ensure that `refresh_watchers` is not
+          # called by a timer.
+          "refresh_interval" => "1h",
+          # stat_watcher often calls `TailWatcher::on_notify` faster than creating a new log file,
+          # so disable it in order to reproduce the same condition stably.
+          "enable_stat_watcher" => "false",
+        }
+      )
+      d = create_driver(config, false)
+
+      tail_watchers = []
+      stub.proxy(d.instance).setup_watcher do |tw|
+        tail_watchers.append(tw)
+        tw
+      end
+
+      Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f| f.puts "file1 log1"}
+
+      d.run(expect_records: 4, timeout: 10) do
+        # Rotate (If the timing is bad, `TailWatcher::on_notify` might be called between mv and new-file-creation)
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f| f.puts "file1 log2"}
+        FileUtils.move("#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt" + "1")
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f| f.puts "file2 log1"}
+
+        # This reproduces the following situation:
+        #     Rotation => refresh_watchers => update_watcher
+        # This add a new TailWatcher: TailWatcher(path: "tail.txt", inode: inode_1)
+        #     This overwrites `@tails["tail.txt"]`
+        d.instance.refresh_watchers
+
+        # `watch_timer` calls `TailWatcher::on_notify`, and then `update_watcher` updates the TailWatcher:
+        #     TailWatcher(path: "tail.txt", inode: inode_0) => TailWatcher(path: "tail.txt", inode: inode_1)
+        # The old TailWathcer is detached here since `rotate_wait` is just `1s`.
+        sleep 3
+
+        # This adds a new TailWatcher: TailWatcher(path: "tail.txt1", inode: inode_0)
+        d.instance.refresh_watchers
+
+        # Append to the new current log file.
+        Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f| f.puts "file2 log2"}
+      end
+
+      inode_0 = tail_watchers[0].ino
+      inode_1 = tail_watchers[1].ino
+      record_values = d.events.collect { |event| event[2]["message"] }.sort
+      position_entries = []
+      Fluent::FileWrapper.open("#{@tmp_dir}/tail.pos", "r") do |f|
+        f.readlines(chomp: true).each do |line|
+          values = line.split("\t")
+          position_entries.append([values[0], values[1], values[2].to_i(16)])
+        end
+      end
+
+      assert_equal(
+        {
+          # TODO: This is BUG!! We need to fix it and replace this with the next.
+          record_values: ["file1 log1", "file1 log1", "file1 log2", "file1 log2", "file2 log1", "file2 log2"],
+          # record_values: ["file1 log1", "file1 log2", "file2 log1", "file2 log2"],
+          tail_watcher_paths: ["#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt", "#{@tmp_dir}/tail.txt1"],
+          tail_watcher_inodes: [inode_0, inode_1, inode_0],
+          tail_watcher_io_handler_opened_statuses: [false, false, false],
+          # TODO: This is BUG!! We need to fix it and replace this with the next.
+          position_entries: [
+            ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+            ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
+            ["#{@tmp_dir}/tail.txt1", "0000000000000016", inode_0],
+          ],
+          # position_entries: [
+          #   ["#{@tmp_dir}/tail.txt", "ffffffffffffffff", inode_0],
+          #   ["#{@tmp_dir}/tail.txt", "0000000000000016", inode_1],
+          # ],
+        },
+        {
+          record_values: record_values,
+          tail_watcher_paths: tail_watchers.collect { |tw| tw.path },
+          tail_watcher_inodes: tail_watchers.collect { |tw| tw.ino },
+          tail_watcher_io_handler_opened_statuses: tail_watchers.collect { |tw| tw.instance_variable_get(:@io_handler)&.opened? || false },
+          position_entries: position_entries
+        },
+      )
+    end
+  end
 end