A dual-band frequency converter unit, for selectively performing frequency conversion between a 2.4-GHz high-frequency-band signal or a 5-GHz high-frequency-band signal and a baseband signal by frequency mixing, includes a local oscillator for generating a local oscillation signal; a first frequency divider for generating a half-frequency signal of the local oscillation signal; and a second frequency divider for generating a quarter-frequency signal of the local oscillation signal. Frequency conversion between the 2.4-GHz high-frequency-band signal and the baseband signal is performed by frequency mixing using the half-frequency signal of the local oscillation signal. Frequency conversion between the 5-GHz high-frequency-band signal and the baseband signal is performed by frequency mixing using the local oscillation signal and the quarter-frequency signal of the local oscillation signal.