To suppress the capacity of memory to be used, and to reduce the deterioration of performance of picture display at the time of using a display controller which is not provided with any dedicated hardware for displaying a cursor.

Data in a frame buffer 16 are preserved as a backup only for an area to display a cursor so that it is not necessary to prepare two frame buffer, and it is possible to reduce a memory capacity almost into half. Also, at the time of changing a picture, whether or not the changed area is overlapped on the cursor display area is judged by an overlap judging part 14, and when those areas are not overlapped, it is possible to process the change of a screen with the same overhead as the case when the cursor is not displayed only by rewriting the changed area of the frame buffer 16.