PURPOSE: To precisely correct the frequency of a reference signal by generating an amount of correction for correcting the reference signal by using the frequency of intermediate frequency by locally oscillated frequency generated on the basis of the reference signal and the known frequency of a received signal and the known locally oscillated frequency.

CONSTITUTION: A second local oscillator 13a generates second locally oscillated frequency on the basis of the reference signal a reference signal generator 11 outputs. A frequency measurement circuit 14a measures second intermediate frequency by using the reference signal. A reference signal correction circuit 15a calculates a correction value by using operation different from the conventional case. Now, if the frequency f'REF of the reference signal deviates from its original value fREF, and falls into the relation of f'REF=α.fREF, the reference signal correction circuit 15a calculates the value of α by using the measured second intermediate frequency, known and original first locally oscillated frequency, the known and original second locally oscillated frequency, and the frequency to be received. Since the original value of α is '1', the correction value to eliminate the difference of the value of α and the original value '1' is given to the reference signal generator 11.