When a power source voltage is applied to a switch control section, a control signal is supplied from the switch control section to a transistor. The transistor is placed in an ON state during a period of time corresponding to a pulse width of the control signal. The power source voltage is applied as a first voltage to a solenoid coil. On the other hand, when supply of the control signal to the transistor is stopped, the transistor is placed in an OFF state. A voltage-generating section generates a DC voltage, which is lower than the power source voltage. The transistor applies the generated DC voltage as a second voltage to the solenoid coil.