PURPOSE: To improve the 1st local oscillating frequency as required according to the frequency fluctuation of the 2nd oscillator by detecting the oscillating frequency of the 2nd local oscillator at the 3rd mixer so as to correct the detected frequency error at a PLL loop including the 1st local oscillator.

CONSTITUTION: A reception signal applied to an input terminal 1 is fed to the 1st mixer 3 via an input BPF2, the signal is converted into the 1st IF by the local oscillating frequency of the 1st local oscillator 6, subjected to the 1st IF amplification 9 and fed to the 2nd mixer 11. The result is converted into the 2nd IF at the mixer 11 by using the local oscillating frequency of the 2nd local oscillator 12 and the 2nd IF is outputted from an output terminal 14. The frequency of the oscillator 12 is fed to the 3rd mixer 20 and converted into the 3rd IF by using the oscillation frequency of the oscillator 1. The 3rd IF is fed to a prescaler 70 and a PLL5 including the oscillator 6 is controlled by utilizing the relation of frequency between the 1st and 2nd oscillators. Further, generation of beat and spurious operation is suppressed corresponding to the frequency fluctuation of the oscillator 2.