To make a synchronizing word detection characteristic excellent by performing the timing decision and control of a reception frame based on a synchronizing word detection information and extracting reception information from the output of a demodulation means accompanying a maximum series estimation.

A reception signal 1 is inputted in a detector 2 of one symbol unit and a detector 6 accompanying a maximum series estimation, the detector 2 detects the reception signal by the one symbol unit by a delay detection and a differential phase signal 3 is outputted. This signal 3 is inputted in a mapping circuit 14 and the corresponding bit series is outputted. At this stage, the output 11 is made to be inputted in a frame synchronizing word detector 12 via a delay element 10 for matching the timing of a detection output bit series 5 of one symbol unit with the timing of the output bit series 9 of the detector 6. As a result, a synchronizing control means 16 performs the timing decision control of a reception frame based on detection information and a reception information extraction means 18 extracts reception information from the output of a demodulation means.