A projector includes: a position detection unit which detects a position pointed by a light pen (first pointer) and a position pointed by a user's finger or the like (second pointer) within a detection area; a state determination unit which determines a pointing direction of the light pen; and an invalid area setting unit which sets an invalid area where the position pointed by the second pointer is invalid, within the detection area, based on the position pointed by the light pen detected by the position detection unit and the pointing direction of the light pen determined by the state determination unit.