In order to enable any user to perform an input operation intuitively and safely in a situation where input operation is required, the control device detects an subject entering a projection range based on the characteristics of subjects included in image data generated by controlling an imaging device, controls a projection device to project projection light on a projection surface so that display information for receiving input is displayed over the projection surface, detects when a pointing body has entered the area above the projection surface based on the image data, identifies the content of an instruction based on the positional relation between the display information displayed over the projection surface and the instructing portion of the pointing body, controls a communication device to transmit the identified instruction content as input information, and controls the projection device not to project the projection light on a projection-prohibited surface.