Abstract: The screen layout of a main screen and a subscreen is optimized, depending on the types of images to be displayed on the main screen and the subscreen. A video terminal, capable of displaying a subscreen within a main screen, is equipped with a signal control unit 15 as means for optimizing the main screen/subscreen layout, depending on the types of images to be displayed on the main screen and the subscreen. When the main screen is in a split composite screen mode, the signal control unit 15 allows a subscreen to be displayed on a screen of a television 11, with the subscreen occupying one section of the split composite screen. When the main screen is in a full screen mode, the signal control unit 15 allows a subscreen to be diminished.