The cluster is formed in such a way that two molecules of arylamine compounds in each of which two arylamines each having one phenyl group and two aryl groups bonded with a nitrogen atom form a bisphenyl bond through the respective phenyl groups are arranged in parallel, thereby forming a dimolecular body and that the dimolecular body is coordinated to metal oxide. The light-emitting element has a layer including the cluster. A manufacturing method thereof includes the steps of vaporizing simultaneously metal oxide and an arylamine compound in which two arylamines each having one phenyl group and two aryl groups bonded with a nitrogen atom form a bisphenyl bond through the respective phenyl groups under vacuum and solidifying simultaneously the vaporized metal oxide and arylamine compound.