PURPOSE: To obtain a shared antenna device with simply constituted transmitter filter.

CONSTITUTION: In the present transmitter filter for a shared antenna device, the first parallel resonance circuit 20 and a capacitor C2 are connected in series between the branch section 2 to which the antenna 1 is connected and a terminal 3 to which a transmitter device is connected. Further, the shared antenna device is provided with the second parallel resonance circuit 21 which is connected with the resonance circuit 20. The resonance circuit 20 resonates at a higher harmonic sending frequency, and the resonance circuit 21 at a receiving frequency. Furthermore, a circuit where the insertion impedance is made small at a transmitter frequency is formed equivalently using the resonance circuit 20, a resonance circuit 21, and a capacitor C2. Resonance circuits 20 and 21 block the higher harmonics of transmitter signal and the receiving signal and permits passing of only the transmitter signal. Accordingly, since the circuit constitution of the present transmitter filter is made simple and coils and capacitors used are small in numbers, it can contribute to making the shared antenna device compact, and as well as to reducing the cost thereof.