PURPOSE: To prevent destruction of circuit elements due to overcurrent, by operating a current limiting circuit and limiting a current of an output transistor (TR), when a voltage difference between a circuit power supply at the prestage from the output TR and a base voltage of the output TR is a prescribed value or over.

CONSTITUTION: An input signal is amplified at a differential amplifier consisting of differential TRs Q1, Q2 and a current source I0. One of the outputs of the differential amplifier becomes a drive input of output TRs Q4 and Q5 of Darlington connection. The other becomes a drive input to output TRs Q6, Q7 in Darlignton connection via a current mirror circuit consisting of resistors R3, R4, a diode D3 and a TRQ3. TRs Q8, Q9 are provided to prevent overcurrent to the TRs Q5, Q7. Circuit power supplies ±B1 of the output TRs Q5, Q7 are increased by prescribed values ±E1 through level shift, allowing to increase the open loop gain.