A novel binuclear metal complex according to the present invention is an asymmetric binuclear metal complex represented by the general formula: (L1)2M1(BL)M2(L2)2(X)n, wherein M1 and M2, which may be identical or different, represent a transition metal; L1 and L2, which are different, represent a chelate ligand capable of polydentate coordination and two L1s may be different and two L2s may be different; BL represents a bridge ligand having at least two heteroatom-containing cyclic structures, the heteroatoms contained in the cyclic structures being ligand atoms coordinating to M1 and M2; X represents a counter ion; and n is the number of counter ions needed to neutralize the charge of the complex. And the binuclear metal complex is useful as a metal complex dye.