The portion corresponding to a main bang signal leaking from a transmission/reception switching unit is extracted as a frequency estimation signal from an IF signal from a mixer in a signal extracting unit, a frequency is estimated in a frequency estimating unit, and the frequency of a local oscillation signal of a local oscillator is controlled so that the frequency of the IF signal is equal to a target value. The frequency estimation in the frequency estimating unit is carried out by using Discrete Fourier Transform or Fast Fourier Transform.