An AGC circuit, which does not require any signal integration circuit comprised of a capacitor and a resistor, is provided. To achieve the above object, when amplifying or attenuating input signal by a variable gain control circuit controlled by the gain control voltage, output signal of the variable gain amplifier circuit is rectified by a rectification circuit, the output signal of the rectification circuit is compared to an arbitrary set voltage by a voltage comparator. The up-count operation and the down-count operation of the up/down counter is controlled to changeover by the output signal of the voltage comparator, and a voltage corresponding to the count value of the up/down counter is output from the D/A conversion circuit. Thus, gain control voltage corresponding to the voltage output from the D/A conversion circuit is supplied to the variable gain amplifier circuit.