PURPOSE: To provide an irreversible circuit element capable of reducing the number of parts and obtaining correct cross angle of center conductors.

CONSTITUTION: Conductor patterns 111a, 111b and 111c constituting parallel conductor patterns constituting one part of center conductors and the electrodes of capacitors and a resistor 113 are printed and formed on dielectric substrates 110 on both sides, a microwave ferrite 120, permanent magnet 140 and conductor board 130 are arranged above and under it, they are housed in shield cases 151 and 152, thus an isolator element is constituted. Thus, the dispersion of characteristics for each element can be reduced and further, parts cost and manufacturing cost can be reduced.