To provide a QPSK/QAM synchronism acquisition device which can continue to synchronize a QPSK/QAM signal in a continuous signal form without using a VCO.

A digital phase modulation signal is subjected to quasi- synchronous detection, and a quasi-synchronous detection output signal is sampled and quantized and is inputted to waveform shaping filters 17 and 18. Tap coefficients of waveform shaping filters can be updated in accordance with the output of a ROM 24, and the internal state of filters can be advanced or delayed by a positive number-fold time of an operation clock in accordance with a delay control signal which a control circuit 23 outputs.