A rare-earth ternary complex represented by the following general formula (1): (1) [wherein M represents a rare earth atom; n1 is 2 or 3; n2 is 2, 3, or 4; Rf and Rf are the same or different and each represents a C1-12 aliphatic group containing no hydrogen atom, an aromatic group containing no hydrogen atom, or an aromatic heterocyclic group containing no hydrogen atom; and Z represents a ligand comprising X, phosphorus, or nitrogen.]