A video combining apparatus to superimpose a virtual image such a CG image on a video image of the real world or on a see-through type display device. An area in which the virtual image is not to be displayed can be easily designated by a user. If the user holds a frame with markers in his/her sight, the frame is image-sensed in the video image of the real world. The area designated by the user is detected by detecting the position of the marker in the video image, and the virtual image is not superimposed in this area.