To reduce the size of a circuit for clamping a surge voltage being generated when a current supply to a load coil is interrupted.

The circuit for clamping a surge voltage being generated when current supply to a load coil is turned off is provided with a switching transistor 2 for turning the current supply to load coil on/off and receiving an on/off control signal at the base thereof. A clamp control transistor 6 has polarity reverse to that of the switching transistor 2 and it is turned on by a surge voltage generated in the load coil to feed an collector current to the base of switching transistor 2.