diff --git a/SFZ_MIDI_Player/Main.cpp b/SFZ_MIDI_Player/Main.cpp
index d8d3e5b..29b5099 100644
--- a/SFZ_MIDI_Player/Main.cpp
+++ b/SFZ_MIDI_Player/Main.cpp
@@ -32,6 +32,7 @@ void Main()
 	Optional<MidiData> midiData;
 
 	DragDrop::AcceptFilePaths(true);
+	Window::SetTitle(U"MIDIファイルをドラッグドロップして再生");
 
 	while (System::Update())
 	{
@@ -83,14 +84,14 @@ void Main()
 		if (midiData)
 		{
 			pianoRoll.updateTick(midiData.value());
+		}
 
 #ifdef LAYOUT_HORIZONTAL
-			pianoRoll.drawHorizontal(player.keyMin(), player.keyMax(), midiData.value());
-			player.drawHorizontal(pianoRoll, midiData.value());
+		pianoRoll.drawHorizontal(player.keyMin(), player.keyMax(), midiData);
+		player.drawHorizontal(pianoRoll, midiData);
 #else
-			pianoRoll.drawVertical(player.keyMin(), player.keyMax(), midiData.value());
-			player.drawVertical2(pianoRoll, midiData.value());
+		pianoRoll.drawVertical(player.keyMin(), player.keyMax(), midiData);
+		player.drawVertical(pianoRoll, midiData);
 #endif
-		}
 	}
 }
diff --git a/SFZ_MIDI_Player/include/PianoRoll.hpp b/SFZ_MIDI_Player/include/PianoRoll.hpp
index 982d4a3..b9a9d80 100644
--- a/SFZ_MIDI_Player/include/PianoRoll.hpp
+++ b/SFZ_MIDI_Player/include/PianoRoll.hpp
@@ -14,9 +14,9 @@ class PianoRoll
 		m_measureWidth(measureWidth)
 	{}
 
-	void drawVertical(int keyMin, int keyMax, const MidiData& midiData) const;
+	void drawVertical(int keyMin, int keyMax, const Optional<MidiData>& midiData) const;
 
-	void drawHorizontal(int keyMin, int keyMax, const MidiData& midiData) const;
+	void drawHorizontal(int keyMin, int keyMax, const Optional<MidiData>& midiData) const;
 
 	void updateTick(const MidiData& midiData);
 
diff --git a/SFZ_MIDI_Player/include/SamplePlayer.hpp b/SFZ_MIDI_Player/include/SamplePlayer.hpp
index 1822c04..b469e31 100644
--- a/SFZ_MIDI_Player/include/SamplePlayer.hpp
+++ b/SFZ_MIDI_Player/include/SamplePlayer.hpp
@@ -41,9 +41,9 @@ class SamplePlayer
 
 	RectF getHorizontalRect(int octaveIndex, int noteIndex, bool isWhiteKey) const;
 
-	void drawVertical2(const PianoRoll& pianoroll, const MidiData& midiData) const;
+	void drawVertical(const PianoRoll& pianoroll, const Optional<MidiData>& midiData) const;
 
-	void drawHorizontal(const PianoRoll& pianoroll, const MidiData& midiData) const;
+	void drawHorizontal(const PianoRoll& pianoroll, const Optional<MidiData>& midiData) const;
 
 	const NoteEvent& addEvent(uint8 key, uint8 velocity, int64 pressTimePos, int64 releaseTimePos);
 
diff --git a/SFZ_MIDI_Player/source/PianoRoll.cpp b/SFZ_MIDI_Player/source/PianoRoll.cpp
index 01379bb..33128c8 100644
--- a/SFZ_MIDI_Player/source/PianoRoll.cpp
+++ b/SFZ_MIDI_Player/source/PianoRoll.cpp
@@ -3,7 +3,7 @@
 #include <MIDILoader.hpp>
 #include <Utility.hpp>
 
-void PianoRoll::drawVertical(int keyMin, int keyMax, const MidiData& midiData) const
+void PianoRoll::drawVertical(int keyMin, int keyMax, const Optional<MidiData>& midiDataOpt) const
 {
 	const double bottomY = m_area.y + m_area.h;
 	const double unitHeight = m_area.h / (keyMax - keyMin + 1);
@@ -13,6 +13,13 @@ void PianoRoll::drawVertical(int keyMin, int keyMax, const MidiData& midiData) c
 	const Color measureFontColor(214, 214, 214);
 	m_area.draw(bgColor);
 
+	if (!midiDataOpt)
+	{
+		return;
+	}
+
+	const auto& midiData = midiDataOpt.value();
+
 	const double widthTick = (midiData.resolution() / 480.0) * m_area.w / m_drawScale;
 
 	const double leftTick = m_currentTick;
@@ -91,7 +98,7 @@ void PianoRoll::drawVertical(int keyMin, int keyMax, const MidiData& midiData) c
 	}
 }
 
-void PianoRoll::drawHorizontal(int keyMin, int keyMax, const MidiData& midiData) const
+void PianoRoll::drawHorizontal(int keyMin, int keyMax, const Optional<MidiData>& midiDataOpt) const
 {
 	const double leftX = m_area.x;
 	const double unitWidth = m_area.w / (keyMax - keyMin + 1);
@@ -99,9 +106,15 @@ void PianoRoll::drawHorizontal(int keyMin, int keyMax, const MidiData& midiData)
 	const Color bgColor(19, 19, 22);
 	const Color measureLineColor(214, 214, 214);
 	const Color measureFontColor(214, 214, 214);
-
 	m_area.draw(bgColor);
 
+	if (!midiDataOpt)
+	{
+		return;
+	}
+
+	const auto& midiData = midiDataOpt.value();
+
 	const double heightTick = (midiData.resolution() / 480.0) * m_area.h / m_drawScale;
 
 	const double bottomTick = m_currentTick;
diff --git a/SFZ_MIDI_Player/source/SamplePlayer.cpp b/SFZ_MIDI_Player/source/SamplePlayer.cpp
index dc04594..478b6da 100644
--- a/SFZ_MIDI_Player/source/SamplePlayer.cpp
+++ b/SFZ_MIDI_Player/source/SamplePlayer.cpp
@@ -230,7 +230,7 @@ RectF SamplePlayer::getHorizontalRect(int octaveIndex, int noteIndex, bool isWhi
 	return RectF(noteLeftX, m_area.y, noteWidth, m_area.h * (isWhiteKey ? 1. : 2. / 3.));
 }
 
-void SamplePlayer::drawVertical2(const PianoRoll& pianoroll, const MidiData& midiData) const
+void SamplePlayer::drawVertical(const PianoRoll& pianoroll, const Optional<MidiData>& midiDataOpt) const
 {
 	const int octaveMin = m_octaveMin + 1;
 	//const int octaveMax = m_octaveMax + 1;
@@ -238,21 +238,23 @@ void SamplePlayer::drawVertical2(const PianoRoll& pianoroll, const MidiData& mid
 	//const double currentTick = pianoroll.currentTick();
 	const double currentSeconds = pianoroll.currentSeconds();
 
-	const auto& tracks = midiData.notes();
-
 	HashTable<int, std::pair<double, int>> pressedKeyTick;
-	for (const auto& [i, track] : Indexed(tracks))
+	if (midiDataOpt)
 	{
-		if (i == 10)
+		const auto& tracks = midiDataOpt.value().notes();
+		for (const auto& [i, track] : Indexed(tracks))
 		{
-			continue;
-		}
+			if (i == 10)
+			{
+				continue;
+			}
 
-		for (const auto& note : track.notes())
-		{
-			if (note.beginSec <= currentSeconds && currentSeconds < note.endSec)
+			for (const auto& note : track.notes())
 			{
-				pressedKeyTick[note.key] = std::make_pair(currentSeconds - note.beginSec, static_cast<int>(i));
+				if (note.beginSec <= currentSeconds && currentSeconds < note.endSec)
+				{
+					pressedKeyTick[note.key] = std::make_pair(currentSeconds - note.beginSec, static_cast<int>(i));
+				}
 			}
 		}
 	}
@@ -329,7 +331,7 @@ void SamplePlayer::drawVertical2(const PianoRoll& pianoroll, const MidiData& mid
 	}
 }
 
-void SamplePlayer::drawHorizontal(const PianoRoll& pianoroll, const MidiData& midiData) const
+void SamplePlayer::drawHorizontal(const PianoRoll& pianoroll, const Optional<MidiData>& midiDataOpt) const
 {
 	const int octaveMin = m_octaveMin + 1;
 	//const int octaveMax = m_octaveMax + 1;
@@ -337,21 +339,23 @@ void SamplePlayer::drawHorizontal(const PianoRoll& pianoroll, const MidiData& mi
 	//const double currentTick = pianoroll.currentTick();
 	const double currentSeconds = pianoroll.currentSeconds();
 
-	const auto& tracks = midiData.notes();
-
 	HashTable<int, std::pair<double, int>> pressedKeyTick;
-	for (const auto& [i, track] : Indexed(tracks))
+	if (midiDataOpt)
 	{
-		if (i == 10)
+		const auto& tracks = midiDataOpt.value().notes();
+		for (const auto& [i, track] : Indexed(tracks))
 		{
-			continue;
-		}
+			if (i == 10)
+			{
+				continue;
+			}
 
-		for (const auto& note : track.notes())
-		{
-			if (note.beginSec <= currentSeconds && currentSeconds < note.endSec)
+			for (const auto& note : track.notes())
 			{
-				pressedKeyTick[note.key] = std::make_pair(currentSeconds - note.beginSec, static_cast<int>(i));
+				if (note.beginSec <= currentSeconds && currentSeconds < note.endSec)
+				{
+					pressedKeyTick[note.key] = std::make_pair(currentSeconds - note.beginSec, static_cast<int>(i));
+				}
 			}
 		}
 	}