A local oscillator outputs a local oscillation signal. A orthogonal detector subjects a received signal to orthogonal detection by using the local oscillation signal so as to output an I-phase baseband signal and a Q-phase baseband signal. A first HPF and a second HPF reduce a direct current component of each of the I-phase baseband signal and the Q-phase baseband signal. A demodulator demodulates the I-phase baseband signal and the Q-phase baseband signal output from the first HPF and the second HPF. A distribution detector detects an unevenness in a distribution of the I-phase baseband signal and the Q-phase baseband signal with the reduced direct current component. When the distribution detector detects an unevenness in the distribution, the distribution detector changes a status of the first HPF and the second HPF.

A local oscillator outputs a local oscillation signal. A orthogonal detector subjects a received signal to orthogonal detection by using the local oscillation signal so as to output an I-phase baseband signal and a Q-phase baseband signal. A first HPF and a second HPF reduce a direct current component of each of the I-phase baseband signal and the Q-phase baseband signal. A demodulator demodulates the I-phase baseband signal and the Q-phase baseband signal output from the first HPF and the second HPF. A distribution detector detects an unevenness in a distribution of the I-phase baseband signal and the Q-phase baseband signal with the reduced direct current component. When the distribution detector detects an unevenness in the distribution, the distribution detector changes a status of the first HPF and the second HPF.