Provided is a control device that projects an image representing input information onto a projection surface so as to follow an input of the input information, with an effect in accordance with the type of the projection surface. As the projection surface, a thin sheet material attached on a wall surface is prepared, for example. The color of the thin sheet material is a dark color, for example, and in time with projection of the image representing a handwritten character or picture, a sound, which will come out when the character or the picture is drawn with a chalk on a chalkboard, is output from a speaker installed on the back side of the projection surface.