PURPOSE: To visually recognize the attribute of a switch and to improve operability by displaying switch patterns in various shapes corresponding to the attributes of operation switches.

CONSTITUTION: In the lower area of a display part 12, switch patterns respectively corresponding to respective operation switches 21-26 are displayed just above these operation switches 21-26. A switch pattern 13 in the first shape is displayed corresponding to the operation switches 21 and 22, a switch pattern 14 in the second shape is displayed corresponding to the operation switches 23 and 24, and a switch pattern 15 in the third shape is displayed corresponding to the operation switches 25 and 26 respectively. The respective shapes of these switch patterns 13-15 respectively show the mutually different switch attributes. Thus, the attribute of the operation switch is visually clearly displayed, and operability can be improved.