Image display system, projection type image display device, and control method for projection type image display device

When an image signal is sent from a mobile terminal (201) to a plurality of projectors (101A - C) wirelessly with conventional technology, there has been a problem that, because of delays caused by the buffering processing differing in the wireless unit (115) for each projector, variations arise in the image output of the projectors, causing failure in image continuity. In the present invention, an image signal (302) sent by the mobile terminal (201) has added thereto information (301) on video time at which the image signal should be output. A maximum image signal delay time T shared by the projectors (101) is added to the video time, and the image signal is output with a delay on the basis of time information shared by the projectors. Thereby, a synchronized image is output and displayed from the plurality of projectors.