PURPOSE: To provide the antenna duplexer in which the configuration of a reception filter is simplified.

CONSTITUTION: A 1st parallel resonance circuit 20 and a capacitor C2 are connected in series between a branch part 2 connecting to an antenna 1 and a terminal 4 connecting to a receiver in a reception filter of the antenna duplexer. Furthermore, a 2nd parallel resonance circuit 21 is coupled with the resonance circuit 20. The resonance circuit 20 is resonated at harmonics of a transmission frequency and the resonance circuit 21 is resonated at the transmission frequency. Moreover, a circuit reducing an insertion impedance at a reception frequency is equivalently formed by the resonance circuit 20, the resonance circuit 21 and the capacitor C2. The resonance circuit 20 and the resonance circuit 21 block the harmonics of the transmission signal and the transmission signal itself and pass only the reception signal. Thus, the circuit configuration is simplified and number of coils and capacitors is less, then the antenna duplexer is made small and the cost is reduced.