An antenna duplexer includes a transmission filter and a reception filter both coupled with an antenna terminal. A pass band of the transmission filter is lower than a pass band of the reception filter. The transmission filter includes a first series resonator coupled with a first terminal, a second series resonator connected to the first series resonator at a first node, a first parallel resonator connected to a first port of the first series resonator, a second parallel resonator connected to a first node and the first parallel resonator at a second node, a third parallel resonator connected to the first node, a fourth parallel resonator connected to the third parallel resonator at a third node, a first inductance element coupled with the second node and a ground, and a second inductance element coupled with the third node and the ground. The first and second parallel resonators and the first inductance element produce an attenuation pole at a frequency lower than a pass band of the transmission filter. The third and fourth parallel resonators and the second inductance element produce an attenuation pole at a frequency higher than a pass band of the transmission filter. The inductance of the second inductance element is lower than the inductance of the first inductance element. In this antenna duplexer, the transmission filter sufficiently suppresses a spurious caused by harmonics contained in a transmission signal.