PURPOSE: To obtain an FM demodulator in which circuit integration is attained and the adjustment is easy by providing a waveform shaping circuit, a sawtooth wave generating circuit and a voltage storage circuit.

CONSTITUTION: A waveform shaping circuit 1 converts an FM input into rectangular wave signals R1...Rn whose duty ratio is 50% and periods are T1...Tn. A sawtooth wave generating circuit 2 uses leading pulses t11...tn1 of the signals R1...Rn to generate sawtooth waves signals S1...Sn changing with a prescribed slope from a prescribed voltage. A voltage storage circuit 3 stores maximum voltages V1...Vn of the sawtooth waves S1...Sn at trailing pulses t12...tn2 of the signals R1...Rn to obtain an FM demodulation output. The circuits 1-3 are constituted with less number of circuit components and the time constant being a product of CR deciding the period of the sawtooth wave of the sawtooth wave generating circuit 2 is one period of the FM wave or so, which is a very small value, then circuit integration is attained and no adjustment is required.