A cyanido-bridged Fe-Nb bimetal assembly, Fe-2[Nb(CN)(8)]-(4-methylpyridine)(8)center dot 2H(2)O, was synthesized. This compound exhibits a two-step spin-crossover phenomenon between Fe-II high-spin (Fe-HS(II), S = 2) and Fe-II low-spin (Fe-LS(II), S = 0) at 112 and 95K. Irradiation with 532-nm light converts the paramagnetic state to a ferrimagnetic state with a Curie temperature of 14K and a coercive field of 2300 Oe. Furthermore, irradiating with 785-nm light reduces magnetization due to the reverse photoinduced spin-crossover phenomenon.