A handwriting detection sheet includes a handwriting layer, a code layer and an optical layer. The handwriting layer can display handwriting. The code layer is placed on a rear-face side of the handwriting layer. The code layer includes plural code images arranged in a matrix manner. In the code images, position codes are encoded with a light absorption material that absorbs infrared light. The optical layer is placed on a rear-face side of the code layer. The optical layer reflects infrared light and allows visible light to pass through.