PURPOSE: To obtain a solenoid driving circuit suitable for control using a microcomputer, and enabled to perform easily start-quickened driving by a method wherein when the microcomputer receives the output signal of a current detecting circuit, a solenoid driving transistor is controlled intermittently, and a current to flow in an exciting coil is changed over a holding current value from an excessive current value.

CONSTITUTION: A solenoid driving transistor 4 is held in an ON condition, and it is awaited that a driving current Ic to reach the current value to satisfy sufficiently the high speed starting condition of a solenoid. When a current detecting circuit 12 detects the fact that an excessive current enabled to perform sufficiently high speed starting is flowed, a microcomputer 1 makes a solenoid driving signal A to ON and OFF at the prescribed period. The solenoid driving transistor 4 is also made to perform ON and OFF action corresponding thereto, and electric power to be applied to an exciting coil 2 from an electric power source +V is made to be intermittent. A current to flow in the exciting coil 2 is made to a current to pulsate at the part sufficiently lower than the excessive current value at initial action starting time, and the average value thereof is made so as to satisfy the holding current value of the solenoid.