PURPOSE: To easily confirm abnormality display without fail by executing display with the maximum brightness of a display regardless of the degree of brightness adjustment in an adjusting means when executing abnormality display by the display.

CONSTITUTION: Even when a control switch 4 is turned on and a seven segment display 7 is used while lowering the brightness of respective LED display elements 7a and 7b constituting the display 7, a microcomputer 1 displays data for error display to warn abnormal heat on the seven-segment display 7 with the maximum brightness in the case of turning an overheat detection thermoswitch 5 off by the abnormal heat of a main body 2 in an air conditioner. Thus, a user can speedily and securely confirm the generation of the abnormal heat and the operation convenience is improved since there is no trouble such as turning the control switch 4 off or making it dark around the display 7 by covering the display with a hand.