PURPOSE: To provide a strip line dual mode filter which can solve such problems as the conventional filter with which a wide pass band is limited, etc., and can be applied to the HPFs of various electrical equipments with high efficiency.

CONSTITUTION: A uniwavelength resonator 101 is provided with four terminals at each 90° in terms of the electric length, and the terminal set at a position distant from the terminal connected to an input inductor 102 at 90° in terms of the electric length is connected to the terminal set at a position of 180° in terms of the electric length via a feedback circuit 106. Then other terminals are connected to the output inductors respectively. In such a constitution, it is possible to obtain a strip line dual mode filter which can control the degrees of coupling in a wide range and with high performance by means of the proper circuit 106 and also can produce the orthogonal mode resonances which are not coupled to each other with regard to a single strip line ring resonator.