Favorable isolation characteristics are obtained over a wide band in a non-reciprocal circuit element. A non-reciprocal circuit element includes: a magnetic material 10 to which a DC magnetic field is applied by a permanent magnet; and a plurality of center electrodes disposed on the magnetic material 10 so as to intersect each other in an insulated state. Of the plurality of center electrodes, a first center electrode 21 is connected at one end thereof to a first input/output port P1, and a second center electrode 22 is connected at one end thereof to a second input/output port P2. A resistance element R is connected in series between the ports P1 and P2, and a phase-shift circuit (a parallel resonant circuit composed of an inductance element L5 and a capacitance element C5) is connected in series with the resistance element R.