A radar device for transmitting a high-frequency transmission signal intermittently in a transmission cycle having a predetermined transmission period and a non-transmission period, receiving a signal reflected by a target by using a plurality of reception antennas, and detecting the target based on the reflected signal, the radar device comprising: a transmission signal generator adapted to generate a transmission signal in baseband; a RF transmitter adapted to convert the transmission signal generated by the transmission signal generator into a high-frequency transmission signal; a directional coupler adapted to distribute the high-frequency transmission signal converted by the RF transmitter in accordance with a predetermined signal power ratio; a level adjuster adapted to attenuate the high-frequency transmission signal distributed by the directional coupler to a predetermined level; a signal combiner adapted to combine a signal output from the level adjuster and a reception signal received by the reception antennas; a RF receiver adapted to convert the signal combined by the signal combiner into a reception signal in the baseband; a reference transmission signal generator adapted to generate a reference transmission signal the same as the transmission signal generated by the transmission signal generator; a correlation value calculator adapted to calculate a correlation value between the reference transmission signal generated by the reference transmission signal generator and the reception signal converted by the RF receiver; a phase shift quantity calculator adapted to calculate a phase shift quantity in arbitrary one of the reception antennas based on the correlation value in a reference reception antenna which is specific one of the reception antennas and the correlation value in any one of the other reception antennas, both correlation values corresponding to the time of the end of the transmission period; and a phase corrector adapted to correct a phase component of the correlation value in the arbitrary reception antenna based on the phase shift quantity calculated by the phase shift quantity calculator. a transmission signal generator adapted to generate a transmission signal in baseband; a RF transmitter adapted to convert the transmission signal generated by the transmission signal generator into a high-frequency transmission signal; a directional coupler adapted to distribute the high-frequency transmission signal converted by the RF transmitter in accordance with a predetermined signal power ratio; a level adjuster adapted to attenuate the high-frequency transmission signal distributed by the directional coupler to a predetermined level; a signal combiner adapted to combine a signal output from the level adjuster and a reception signal received by the reception antennas; a RF receiver adapted to convert the signal combined by the signal combiner into a reception signal in the baseband; a reference transmission signal generator adapted to generate a reference transmission signal the same as the transmission signal generated by the transmission signal generator; a correlation value calculator adapted to calculate a correlation value between the reference transmission signal generated by the reference transmission signal generator and the reception signal converted by the RF receiver; a phase shift quantity calculator adapted to calculate a phase shift quantity in arbitrary one of the reception antennas based on the correlation value in a reference reception antenna which is specific one of the reception antennas and the correlation value in any one of the other reception antennas, both correlation values corresponding to the time of the end of the transmission period; and a phase corrector adapted to correct a phase component of the correlation value in the arbitrary reception antenna based on the phase shift quantity calculated by the phase shift quantity calculator.