A bandpass filter is provided that prevents clock leakage to the input side of an amplifier circuit and has excellent out-of-passband signal attenuation. It includes an amplifier (102) connected between an input terminal and an output terminal, an impedance frequency conversion circuit (101) that is connected between an output of the amplifier and ground and changes impedance depending on whether or not the frequency of a signal output from the amplifier is within a predetermine passband, and a feedback circuit (103) connected between the output and an input of the amplifier.