circuit element is in operation since the magnetic field generated by the magnetic member 2 for nonreciprocal circuit extends externally of the member as shown in fig2 it is varied when the magnetic member 3 is positioned in a position within the magnetic field the variation depending upon the magnetization of the magnetic member 3 and as a result the frequency characteristics of the high frequency nonreciprocal circuit element is changed referring now to fig3 and 4 it is possible to regulate the frequency characteristics by changing the state of magnetization of the magnetic member by externally applying a magnetic field to the high frequency nonreciprocal circuit element constructed as shown in fig1 a to 1 c demagnetizing the magnetic member by increasing the temperature of the magnetic material up to a temperature not lower than curie temperature thereof and then magnetizing it by applying a magnetic field while it is cooled gradually performs the magnetization the state of magnetization of the magnetic member is changed while monitoring the frequency characteristics of the high frequency nonreciprocal circuit element it is possible to change the operating frequency characteristics of the high frequency nonreciprocal circuit element by simultaneously changing the states of magnetization of the magnetic members 2 and 3 however when the change of the magnetization of the magnetic member 2 for nonreciprocal.