A composition comprising: a homo-N-trans iridium complex having an iridium atom, and a first ligand, a second ligand, and a third ligand that are bonded to the iridium atom, the second ligand having the same structure as the first ligand, the third ligand having a different structure from the first and second ligands; and an isomer of the iridium complex, the isomer having an iridium atom, a fourth ligand, a fifth ligand, and the third ligand, the fourth ligand being a ligand represented by the same rational formula as that of the first ligand, and the fifth ligand being a ligand represented by the same rational formula as that of the second ligand, wherein a composition ratio of the isomer relative to a total of the iridium complex and the isomer is 1.0% or less, wherein the iridium complex is an iridium complex represented by general formula or below: where, in general formula and general formula, L represents a bidentate ligand, R 1 to R 18 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a cyano group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group; ring A represents a ring structure that may have a substituent and that is selected from a benzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, a 9,9-spirobifluorene ring, a chrysene ring, and a substituted or unsubstituted heteroaromatic group; and IrL is represented by one of general formulae to below: where, in general formulae to, R 19 to R 33 are each independently selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group. a homo-N-trans iridium complex having an iridium atom, and a first ligand, a second ligand, and a third ligand that are bonded to the iridium atom, the second ligand having the same structure as the first ligand, the third ligand having a different structure from the first and second ligands; and the second ligand having the same structure as the first ligand, the third ligand having a different structure from the first and second ligands; and an isomer of the iridium complex, the isomer having an iridium atom, a fourth ligand, a fifth ligand, and the third ligand, the fourth ligand being a ligand represented by the same rational formula as that of the first ligand, and the fifth ligand being a ligand represented by the same rational formula as that of the second ligand, the fourth ligand being a ligand represented by the same rational formula as that of the first ligand, and the fifth ligand being a ligand represented by the same rational formula as that of the second ligand, wherein a composition ratio of the isomer relative to a total of the iridium complex and the isomer is 1.0% or less, wherein the iridium complex is an iridium complex represented by general formula or below: where, in general formula and general formula, L represents a bidentate ligand, R 1 to R 18 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a cyano group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group; ring A represents a ring structure that may have a substituent and that is selected from a benzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, a 9,9-spirobifluorene ring, a chrysene ring, and a substituted or unsubstituted heteroaromatic group; and IrL is represented by one of general formulae to below: where, in general formulae to, R 19 to R 33 are each independently selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group.