To automatically perform the stoppage or suppression of energizing in a state that the possibility to be used does not exist by transferring a mode to a power saving mode based on a signal from a predictive means predicting a state of no using possibility.

A controller 3 executes a power saving mode when a power saving selective switch 14 is operated and performs an on/off control for a relay 1 by depending on whether or not a voltage value detected between a CDS 9 and resistance 10 of an optical sensor 2 exceeds prescribed threshold. At first, whether a room is bright or dark is judged based on detected voltage. When the room is judged to be dark, a timer is started, a relay 1 is turned off and energizing of a heater 6 is stopped because no using possibility exists. A judgment as to whether the room is bright or dark and a judgment as to whether a release input is performed or not are performed again till set time passes.