To inform an user of the high temperature condition of a heat unit even after power supply is turned off and thereby improve safety, by providing with an informing means which informs that the heat unit in which infrared radiator is built-in is heated.

A temperature indicating area 20 whose color changes according to temperature is formed on a ring-shaped front circumference part of a front face part of a cover 12, in a heat unit 5. Thereby, the user is called attention, and careless touch to the heat unit 5 by the user when it is heated to high temperature is prevented. Especially a ceramic heater which is an infrared radiator does not emit luminescent red color even when power supply is turned 'on', therefore, calling attention to the user is usefull. And also, attention to the user is continued to be called by displaying the caution color to indicate high temperature of the cover 12 which continues for a while after the power supply is turned 'off' by the temperature indicating area 20, because a display lamp is usually turned 'off' as the power supply turned αoff' even when the power supply 'on' displaying lamp is provided with the heater.