CuFe2O4 was synthesized by microwave irradiation and conventional processing. In addition, microwave H-field annealing was conducted in order to investigate the effect of a magnetic field on tetragonal CuFe2O4. The sample synthesized with microwave E-field irradiation was cubic CuFe2O4, had a small saturation magnetization, and the same coercivity as that produced by conventional heating. In contrast, the sample synthesized with H-field irradiation had a larger saturation magnetization and a smaller coercivity than the sample synthesized by conventional heating. After H-field annealing, the sample had a large amount of cubic CuFe2O4 phase that consists of small crystallites. Moreover, the saturation magnetization increased and the coercivity decreased. These results suggest that microwaves lead to a reduction in the Jahn-Teller distortion and the magnetic property changes accordingly. It is concluded that microwaves affect the Jahn-Teller distortion of CuFe2O4 and the effect leads to changes in the phase and magnetic properties.