PURPOSE: To connect a surface acoustic wave(SAW) filter to another electronic circuit with not use of a capacitor by using the input and output buffer circuits having such constitutions that prevent the input/output potential difference of the SAW filter from exceeding the breakdown strength of the filter.

CONSTITUTION: An SAW filter device is provided with an input buffer circuit 2 which receives a signal from the outside and produces an input signal to an SAW filter 1 and an output buffer circuit 3 which receives the output of the filter 1 and produces a signal to the outside. Then both circuits 2 and 3 have such constitutions that prevent the potential difference between the output voltage of the circuit 2 and the input voltage of the circuit 3 from exceeding the breakdown strength of the filter 1. The input of the circuit 2 and the output of the circuit 3 can be directly connected to other circuits like the ordinary electronic circuits. Therefore using a coupling capacitor C that prevents the miniaturization of the filter device is not needed when the filter device is mounted.