PURPOSE: To provide the antenna matching circuit capable of selecting the matching circuit with a highest circuit efficiency in which the impedance between a radio transmitter and one or plural antennas is taken in a short time.

CONSTITUTION: A load detector 5, a matching circuit 4 able to vary the circuit constitution and the circuit component, and switches S1, S2 having a 1st changeover position in which the load detector 5 is directly connected to the antenna 3 while bypassing the matching circuit 4 and having a 2nd changeover position in which the load detector 5 is connected to the antenna 3 via the matching circuit 4 are provided between a radio transmitter 1 and the antenna 3. The switches S1, S2 are switched to the 1st changeover position (bypass position) when a transmission frequency of the radio transmitter 1 is switched to make the load detector 5 measure the impedance of the antenna 3, the circuit constitution of the matching circuit is selected in response to the measured impedance and the frequency at that time, the variable circuit component is adjusted roughly, the switches S1, S2 are switched to the 2nd changeover position (matching circuit position) and the variable circuit component of the matching circuit is fine-adjusted.