PURPOSE: To obtain an excellent bit error rate characteristic by converting a received IF signal into a base band spread spectrum reception signal prior to inverse spread of a PN code in a spread spectrum demodulator, applying accurate waveform shaping in a low pass filter, applying inverse spread finally and outputting the result as a demodulation data.

CONSTITUTION: A circuit 15 is constituted, which multiplies a recovered carrier 14 recovered from an inverse spread signal 12 with a received IF signal 3 before inverse spread and recovers a spread spectrum reception signal of base band. Then the base band spread spectrum reception signal 16 is inputted to a low pass filter 17 to attain accurate waveform shaping close to an ideal characteristic with respect to the reception signal. Thus, accurate waveform shaping almost close to the ideal characteristic is attained prior to the inverse spread of a received signal in the spread spectrum demodulation. Thus, excellent bit error rate characteristic is obtained.