A projector includes: a position detection unit which detects a designated position (XYZ coordinates) designated by a light pen; and a mode changing unit which determines that an operation button provided on the light pen is operated, and which changes a drawing mode if it is determined that the operation button is operated. The mode changing unit: changes the drawing tool if the Z coordinate of the designated position when it is determined that the operation button is operated is within a first distance range; changes the color of the pen if the Z coordinate of the designated position when it is determined that the operation button is operated is within a second distance range; and changes the thickness of the pen or the like if the Z coordinate of the designated position when it is determined that the operation button is operated is within a third distance range.