PURPOSE: To reduce error for setting a bisecting position in the case of bisecting a display picture by displaying a changed firs block area line on third display conditions different from first and second display conditions.

CONSTITUTION: In the bisected display picture, the picture frame of a first display picture 12 to display a current picture is displayed by a thick line, and the picture frame of a second display picture 13 to display a non-current picture is displayed by a thin line. When a picture size setting key is inputted, the lower frame of the picture frame of the first display picture 12 is changed into a broken line 16. When a vertical cursor move key is operated, the broken line 16 is vertically moved. When a current picture size decision key is operated at the time point when the suitable size of the current picture is provided, the broken line 16 is changed into the same thick line as the picture frame of the first display picture of the current picture. Thus, the current picture and the non-current picture can be easily identified. Further, the size to set the current picture can be exactly grasped.