PURPOSE: To attain the reception of broad band and high sensitivity, by providing a phase shifter shifting an amplitude modulation signal by ±90°, in a demodulation circuit using a phase-locked loop.

CONSTITUTION: An AM signal (a) from an input terminal 1 is applied to synchronizing detectors 30, 90 via a -90° phase shifter 20 and a +90° phase shifter 80 respectively to output detected outputs E2, E3. Further, the AM signal (a) is applied to a phase-locked loop 100, where an output signal E1 is outputted. The detected output E2 and the output signal E1 are summed at an adder 16, the detected output E3 and the output signal E1 are summed at an adder 17, and the summed values are given to a changeover switch 12. Input signals are selectively picked up at the switch 12 and given to an LPF4 for demodulation. Thus, the reception of broad band and high sensitivity is performed.