A quadrature detector quadrature-detects an FM signal. An FM detector generates a detection signal by FM detecting an FM signal that has been quadrature-detected. An AFC unit generates a control signal for controlling a frequency of a local oscillation signal used for quadrature detection on the basis of the generated detection signal, and feeds back the control signal to a local oscillator that should output the local oscillation signal. A difference calculator generates a difference signal representing a difference from a reference value on the basis of the generated detection signal. An addition unit adds the generated difference signal and the generated detection signal.