A coordinate detecting apparatus includes: a plurality of light-emitting and -receiving units arranged along an outer edge of the coordinate input area, the plurality of light-emitting and -receiving units each including a light-emitting part and a light-receiving part; at least one retroreflective member arranged along the outer edge of the coordinate input area; and a control unit to control the plurality of light-emitting and -receiving units to detect coordinates of a position of input made with a designation input unit in a first detection state or a second detection state.