We calculated the photonic band gap spectra of a one‐dimensional magnetic photonic crystal made of alternating layers of bigyrotropic magnetic yttrium‐iron garnet and nonmagnetic gadolinium gallium garnet. The forbidden regimes or band gaps in the electromagnetic wave spectrum were numerically obtained for the transversal magneto‐optical configuration and compared with those for the polar and longitudinal magneto‐optical configurations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)