PURPOSE: To eliminate the need to adjust a circuit, to expand an in-use temperature range and to decrease the number of connection terminals by using a current mirror circuit and separating a load and a current detecting circuit.

CONSTITUTION: The output of an error amplifier 9 is inputted to the current mirror circuit 5 which constitute a current limiting element through a current limiting resistance 4, and its output is supplied to the load 7 and the inverted input terminal of the amplifier 9. The output of a reference voltage circuit 2 is supplied to the univerted input terminal of the amplifier 9 through the current detecting circuit 6 composed of a resistance 6. Then, the current of the load 7 is determined by the output voltage of the circuit 2 and the resistance value of the circuit 6.