Light-induced electron transfer reaction within binuclear complex $(NC)_5FeII-L-CoIII(NH_3)_5$ was studied with steady-state photolysis and the rate constants were measured for various bridging lignands. klight and quantum yields for BP, PHEN, DAP having conjugation between metal binding sites were about $3{ imes}10^{-2} sec^{-1}$ and 1, and for BPEA having no conjugation were about $2{ imes}10^{-4} sec^{-1}$ and 0.03. Light-induced electron transfer reaction within binuclear complex was proved to be the chemical mechanism which had charge transfer excited state MLCT*.