PURPOSE: To set a time width of pulse voltage almost equal even in a different frequency by providing a control signal generating circuit for generating a control signal, when charge voltage in a latter half cycle of AC voltage exceeds a predetermined value, and a trigger signal generating circuit for generating a trigger signal input to a phase control circuit by the control signal after predetermined set time.

CONSTITUTION: When a detection signal is generated in a phase detecting circuit 21, at a phase angle delayed by a predetermined phase in a half cycle from the first zero cross point of 1 cycle of an AC power supply 24, a charge is started in a charging circuit 26. When charge voltage reaches a predetermined value by being charged in a voltage direction of a latter half cycle, a control signal is output by a control signal generating circuit 22, and a phase control circuit 25 is turned on by receiving a trigger signal, generated by a trigger signal generating circuit 23, so that a pulse voltage of time width until achievement of the zero cross point of the AC power supply 24 may be applied to an electromagnetic solenoid 1. In this way, a time width of pulse voltage applied to the electromagnetic solenoid 1 can be made almost equal even when the frequency of the AC power supply is different.