HEATER

PURPOSE:To improve the reliability of a switching means turning on/off the supply of electricity to a heating body and to enable equal temperature heating under various temperature conditions by means of the stable operation of the disconnection means. CONSTITUTION:A synchronization circuit 6b generating a signal synchronized with the power source frequency of a commercial power source 5 is mounted to a control part 6 controlling on/off of a relay 4 switching the supply of electricity to the heating body, and the on-control of the relay 4 at the time of starting heating or at the time of normal operation is started at timing when the level of a interrupt port 6c of a microprocessor 6a is changed with a signal generated by the synchronization circuit 6b. The timing of generating an on- command to be given to the relay 4 each time is changed by the amount of prescribed time associated with the power source frequency with respect to the previous on-command generation timing and thus, the actual on-operation of the relay 4 can be prevented from concentrating on the same phase of the commercial power source 5.