During execution of an engine application by an engine unit, a host unit determines a region for host display upon a display screen, wherein the host unit determines the display contents, according to the usage direction of the display screen employed. Subsequently, the unit creates a host image; the unit generates an engine application image, when the operation of the engine application starts. A display image generation means then generates an image during engine application execution wherein the host image and the engine application image are overlapped, so that, in the region wherein the region for host display and the region for engine display are superimposed, priority is given to the engine application image. Thus, along with it being possible to build the device as a whole in a more compact manner, it is also possible to ensure the convenience from the point of view of the user.