A catalyst for the decomposition of formic acid including a dinuclear metal complex represented by a formula (1) below, a tautomer or stereoisomer thereof, or any of their salts, where M1 and M2 are transition metals; Ar is a ligand having aromaticity and may be unsubstituted or substituted; R1 to R27 are each independently a hydrogen atom, an alkyl group, or the like, or R15 and R16 may together form a —CH═CH—, where Hs in the —CH═CH— may be each independently replaced by an alkyl group or the like, and R23 and R24 may together form a —CH═CH—, where Hs in the —CH═CH— may be each independently replaced by an alkyl group or the like; L is an arbitrary ligand or is absent; and m is a positive integer, 0, or a negative integer.