Abstract: Transmission signal generation circuitry generates a transmission chirp, and the transmission chirp is transmitted from a transmission antenna. A reflected wave, from an object to be detected, of the transmission chirp transmitted from the transmission antenna is received by a reception antenna. A mixer mixes the transmission chirp and a reception chirp received by the reception antenna to generate an intermediate frequency signal. Signal processing circuitry obtains, for a plurality of respective analysis periods corresponding to different frequency bands of the transmission chirp, frequency spectral waveforms of the intermediate frequency signal, detects a peak appearing in the plurality of frequency spectral waveforms, and determines, based on variations in peak position among the plurality of frequency spectral waveforms, whether or not the peak is due to a valid object.