To detect a request of a user so as to revise a video image projecting position without the need for the user to have a special device such as a sight line input scouter.

A video projector 1 projects a video image on a projecting screen in a projecting space. A camera 3 photographs a user in the projecting space and the projecting screen. A camera image processing section 4 processes an image of the user photographed by the camera 3 to extract a position on the projecting screen instructed by the user. A camera/projecting space coordinate conversion section 6 converts a two-dimensional coordinate to the extracted position into a three-dimensional coordinate in the projecting space to calculate a projecting direction of the video projector 1 and to generate a processing request for a request of revision into the calculated projecting direction. The video projector 1 revises the projection direction on request when the processing request is a revision request in the projecting direction.