This invention is a filter circuit provided in a radio communication module. First to third conductor patterns (8 to 10) having a length shorter than /4 of a passing wavelength and electromagnetically coupled with each other are formed as distributed line patterns parallel to each other in a dielectric board (2), and a first capacitor (16) and a second capacitor (17) add parallel capacitance to the first conductor pattern (8) and the second conductor pattern (9) having their distal ends short-circuited. The third conductor pattern (10) has its both end opened. As the first conductor pattern (8) and the second conductor pattern (9) carry out inductive operation and the third conductor pattern (10) is capacitive-coupled with these conductor patterns, resonance is made in a band lower than a frequency band prescribed by the length of the lines.