PURPOSE: To form a small-sized automatic variable resistor circuit with high accuracy by varying the frequency divider ratio of two variable frequency dividers of a capacitor type amplifier circuit.

CONSTITUTION: The circuit consists of an oscillator 1 whose oscillating frequency is f0, variable frequency dividers 2, 3 frequency-dividing said frequency f0 into 1/M and 1/N respectively, switched capacitor circuits 4, 5 and an operational amplifier 6, the signal level from an input terminal 10 is varied and outputted from an output terminal 11. The frequency divider ratio of the variable frequency dividers 2, 3 is varied to vary the gain. Since the gain is decided by the frequency divider ratio, the small-sized automatic variable resistor circuit with high accuracy is obtained.