1. A presentation system comprising: a screen; a laser pointer operated by a user to project laser beam on the screen; and an infrared light projector for emitting infrared light on the entire surface of the screen; wherein the laser pointer comprises: an infrared light receiving section directed in the same direction as a projection direction of laser beam for receiving infrared light projected from the infrared light projector and reflected from the screen; and a control section for causing the laser pointer to project laser beam only while the infrared light receiving section is receiving infrared light.