PURPOSE: To compensate temperature characteristics of an avalanche diode, and to improve characteristics of a circuit, by providing a resistance between the collector of a transistor and the cathode of its diode, and providing a resistance having a positive temperature coefficient between its cathode and the ground.

CONSTITUTION: A transistor TR1 for switching a current of a load 5 is provided, and one end of a resistance 8 is connected to the collector of this TR1. Also, the cathode of an avalanche diode 4 is connected to the other end of the resistance 8, the anode of the diode 4 is connected to the base of the TR1, and a switching signal from an input terminal 2 is inputted to the base of the TR1. Also, a resistance 9 having a positive temperature coefficient is connected between the cathode of the diode 4 and the emitter of the TR1. In this state, characteristics of a switching circuit are improved by compensating a temperature characteristic of the diode 4 in case when the operation ambient temperature rises by the resistance.