PURPOSE: To keep the frequency characteristic even when a load resistance is changed by detecting a voltage drop across an output resistor and applying feedback to a true output voltage of a discrete output amplifier so as to compensate the DC characteristic.

CONSTITUTION: An output terminal of a main amplifier 12 is connected to a load 20 via a resistor 16. A 1st operational amplifier 26 detects a voltage difference across the resistor 16, and a 2nd operational amplifier 32 receives an output signal of the amplifier 26 and an input signal to the main amplifier 12. For example, the main amplifier 12 is a discrete amplifier, its frequency characteristic is excellent more than that of the amplifiers 26, 32, and on the other hand, the DC characteristic of the amplifiers 26, 32 is excellent more than that of the main amplifier 12. Then the DC level of the main amplifier 12 is corrected by an output signal of the amplifier 32. Thus, the frequency characteristic of the amplifier circuit is improved independently of the load resistor and its DC characteristic is improved.