To enable a portable communication device to select the optimum antenna characteristic to respective transmission conditions.

An earphone microphone detection circuit 2 detects whether an earphone microphone is connected to an earphone jack 10 or not. An antenna matching switching circuit 1 is capable of switching the condition of impedance matching between an antenna 7 and a transmitter-receiver 6. The antenna matching switching circuit 1 switches impedance matching to a state in which a main body microphone is in use when it is not detected by the earphone microphone detection circuit 12 that the earphone microphone is connected and switches impedance matching to a state in which an earphone microphone is in use when it is detected by the earphone microphone detection circuit 2 that the earphone mike is connected.