PURPOSE: To display plural display modes in the center of the screen of one display device and to eliminate the need for a special signal interface by detecting and correcting a display position on the screen at display timing.

CONSTITUTION: A display controller 19 sends the composite video signal 13 of a display position signal 11 and a video signal 12 to a display device 20. The display device 20 separates and regenerates a display position signal 11 from the composite video signal 13 by a separating and regenerating circuit 14 and outputs it to a horizontal timing detecting circuit 18 and after the phase difference is detected and held together with a horizontal synchronizing signal 4, a timing signal is outputted to a horizontal deflecting circuit 7 so that an image to be displayed is displayed in the center of the screen according to the phase difference. Consequently, plural display modes which differ in horizon tal timing are displayed on one display device and the display position of a screen in each display mode is placed in the center of the screen without requir ing any special cable as the signal cable connecting the controller and display device.