To obtain excellent operability for a display of a menu screen which has many control items through easy constitution.

When a process is started, it is judged in a step (1) whether or not an operation key for starting the menu display is operated. When the operation key for the menu display is not operated (N), another process is performed in a step (2) and the process is ended. When the operation key for the menu display is operated in the step (1) (Y), the continuance T of the key operation is judged in a step (3). When the operation time is ≤3 seconds (Y), a screen of MENU 1 is displayed in a step (4). Further, when the operation time T is >3 seconds (N), a screen of MENU2 is displayed in a step (5).