PURPOSE: To prevent the inversion at BPSK demodulation by having only to add a simple configuration component to a receiver side.

CONSTITUTION: An input BPSK signal is demodulated by a BPSK demodulator 2. Furthermore, the input BPSK signal is detected by a carrier detection circuit 3, compared with a detection level set by resistors 34, 35 at a comparator 36, which provides a carrier detection output. A one-shot pulse circuit 4 generates a negative pulse having a predetermined pulse width at the leading of the detection output and gives the pulse to an inversion correction circuit 5. A D flip-flop 51 of the inversion correction circuit 5 latches a demodulation signal at said leading of the pulse. The latched high level signal and the demodulation signal are given to an exclusive OR circuit 52, from which a correct demodulation signal with corrected inversion is outputted.