To automatically determine allocation of images on each projection surface, by distinguishing a projection range of each projection surface, when projecting different images on two projection surfaces.

An imaging part (20) takes an image of an area including a projection range on projection surfaces (12A, 12B) projected by a projection part (18). An imaging signal processing part (22) generates a signal indicating the projection range by processing output from the imaging part (20). A projection image output part (10) supplies image signals for a main image and a user interface (UI) to an image signal processing part (16). The image signal processing part (16) determines allocation of the main image signal and the UI image signal supplied from the projection image output part (10) to the projection surfaces (12A, 12B) in accordance with the signal from the imaging signal processing part (22), and overlaps the image signals according to the allocation to supply the overlapped image signal to the projection part (18).