diff --git a/Siv3D/include/Siv3D/Rect.hpp b/Siv3D/include/Siv3D/Rect.hpp
index 1a54ab015..cae41b378 100644
--- a/Siv3D/include/Siv3D/Rect.hpp
+++ b/Siv3D/include/Siv3D/Rect.hpp
@@ -524,6 +524,30 @@ namespace s3d
 		[[nodiscard]]
 		constexpr Rect stretched(value_type top, value_type right, value_type bottom, value_type left) const noexcept;
 
+		/// @brief 上方向に拡大縮小した長方形を返します。
+		/// @param top 上方向の拡大縮小量
+		/// @return 上方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr Rect stretched(Arg::top_<value_type> top) const noexcept;
+
+		/// @brief 右方向に拡大縮小した長方形を返します。
+		/// @param right 右方向の拡大縮小量
+		/// @return 右方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr Rect stretched(Arg::right_<value_type> right) const noexcept;
+
+		/// @brief 下方向に拡大縮小した長方形を返します。
+		/// @param bottom 下方向の拡大縮小量
+		/// @return 下方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr Rect stretched(Arg::bottom_<value_type> bottom) const noexcept;
+
+		/// @brief 左方向に拡大縮小した長方形を返します。
+		/// @param left 左方向の拡大縮小量
+		/// @return 左方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr Rect stretched(Arg::left_<value_type> left) const noexcept;
+
 		[[nodiscard]]
 		constexpr RectF scaled(double s) const noexcept;
 
diff --git a/Siv3D/include/Siv3D/RectF.hpp b/Siv3D/include/Siv3D/RectF.hpp
index 18721b5d2..d7110ead7 100644
--- a/Siv3D/include/Siv3D/RectF.hpp
+++ b/Siv3D/include/Siv3D/RectF.hpp
@@ -576,6 +576,30 @@ namespace s3d
 		[[nodiscard]]
 		constexpr RectF stretched(value_type top, value_type right, value_type bottom, value_type left) const noexcept;
 
+		/// @brief 上方向に拡大縮小した長方形を返します。
+		/// @param top 上方向の拡大縮小量
+		/// @return 上方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr RectF stretched(Arg::top_<value_type> top) const noexcept;
+
+		/// @brief 右方向に拡大縮小した長方形を返します。
+		/// @param right 右方向の拡大縮小量
+		/// @return 右方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr RectF stretched(Arg::right_<value_type> right) const noexcept;
+
+		/// @brief 下方向に拡大縮小した長方形を返します。
+		/// @param bottom 下方向の拡大縮小量
+		/// @return 下方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr RectF stretched(Arg::bottom_<value_type> bottom) const noexcept;
+
+		/// @brief 左方向に拡大縮小した長方形を返します。
+		/// @param left 左方向の拡大縮小量
+		/// @return 左方向に拡大縮小した長方形
+		[[nodiscard]]
+		constexpr RectF stretched(Arg::left_<value_type> left) const noexcept;
+
 		[[nodiscard]]
 		constexpr RectF scaled(double s) const noexcept;
 
diff --git a/Siv3D/include/Siv3D/detail/Rect.ipp b/Siv3D/include/Siv3D/detail/Rect.ipp
index 53300fafb..6fd26a279 100644
--- a/Siv3D/include/Siv3D/detail/Rect.ipp
+++ b/Siv3D/include/Siv3D/detail/Rect.ipp
@@ -586,6 +586,26 @@ namespace s3d
 		return{ (pos.x - left), (pos.y - top), (size.x + left + right), (size.y + top + bottom) };
 	}
 
+	inline constexpr Rect Rect::stretched(Arg::top_<value_type> top) const noexcept
+	{
+		return stretched(top.value(), 0, 0, 0);
+	}
+
+	inline constexpr Rect Rect::stretched(Arg::right_<value_type> right) const noexcept
+	{
+		return stretched(0, right.value(), 0, 0);
+	}
+
+	inline constexpr Rect Rect::stretched(Arg::bottom_<value_type> bottom) const noexcept
+	{
+		return stretched(0, 0, bottom.value(), 0);
+	}
+
+	inline constexpr Rect Rect::stretched(Arg::left_<value_type> left) const noexcept
+	{
+		return stretched(0, 0, 0, left.value());
+	}
+
 	inline constexpr RectF Rect::scaled(const double s) const noexcept
 	{
 		return{ Arg::center((pos.x + size.x * 0.5), (pos.y + size.y * 0.5)), (size.x * s), (size.y * s) };
diff --git a/Siv3D/include/Siv3D/detail/RectF.ipp b/Siv3D/include/Siv3D/detail/RectF.ipp
index b28fbf295..93ea884e6 100644
--- a/Siv3D/include/Siv3D/detail/RectF.ipp
+++ b/Siv3D/include/Siv3D/detail/RectF.ipp
@@ -642,6 +642,26 @@ namespace s3d
 		return{ (pos.x - left), (pos.y - top), (size.x + left + right), (size.y + top + bottom) };
 	}
 
+	inline constexpr RectF RectF::stretched(Arg::top_<value_type> top) const noexcept
+	{
+		return stretched(top.value(), 0, 0, 0);
+	}
+
+	inline constexpr RectF RectF::stretched(Arg::right_<value_type> right) const noexcept
+	{
+		return stretched(0, right.value(), 0, 0);
+	}
+
+	inline constexpr RectF RectF::stretched(Arg::bottom_<value_type> bottom) const noexcept
+	{
+		return stretched(0, 0, bottom.value(), 0);
+	}
+
+	inline constexpr RectF RectF::stretched(Arg::left_<value_type> left) const noexcept
+	{
+		return stretched(0, 0, 0, left.value());
+	}
+
 	inline constexpr RectF RectF::scaled(const double s) const noexcept
 	{
 		return{ Arg::center((pos.x + size.x * 0.5), (pos.y + size.y * 0.5)), (size.x * s), (size.y * s) };