A Faraday rotator of a hard magnetic Bi-substituted rare earth iron garnet material with excellent Faraday rotary moment, temperature property, wavelength property and insertion loss is provided. A Bi-substituted rare earth iron garnet material having a chemical composition of (Bi3-a-b-cGdaTbbYbc) Fe(5-w)MwO12 (where, M is at least one element selected from the group consisting of Ga, Al, Ge, Sc, In, Si and Ti, 0.5<=a+b+c<=2.5, 0.2<=w<=2.5) can be provided with hard magnetism and have excellent Faraday rotary moment, temperature property, wavelength property and insertion loss. |