PURPOSE: To realize simultaneous display of two or more videos by masking a part of a film or a lens to from an unprojected part on a screen and projecting a video from another projector on the unprojected part and composing.

CONSTITUTION: A photographed film used in a projector 6 or a lens provided in the projector 6 is provided with a black mask that intercepts a part of projection. When a video film is projected from the projector 6, the masked part forms an unprojected from the projector 6, the masked part forms an unprojected part 11 on the screen 1. A composed video is obtained on the same screen by projecting a video or picture of another projector 6 on the unprojected part 11 on the screen 1. By this way, it is possible to display two or more videos or pictures on the same screen simultaneously as need.