A projection system includes a light source, an imaging unit, a control unit, and a projecting unit. The light source applies a light beam having a predetermined wavelength. The imaging unit captures a subject to which the light beam is applied. The control unit generates image data for projection based on the captured image. The projecting unit projects a projection image onto the subject. The imaging unit captures the projection image together with an image of a region responding to the light beam. The control unit corrects the image data for projection to additionally display the projection image on a region which responds to the light beam and does not overlap a region onto which the projection image is projected, and to erase the projection image in a region onto which the projection image is projected and does not overlap the region responding to the light beam.
