An organic light-emitting device comprising an anode, a cathode, and a light-emitting layer interposed between the anode and the cathode, the light-emitting layer including a guest molecule and a host molecule, wherein the guest molecule is an iridium complex represented by Formula, IrL m L' n where Ir represents iridium; L and L' each represent a different bidentate ligand, at least one of L and L' including an alkyl group; m is 2; and n is 1, wherein IrL m is represented by Formula, where R 11 to R 14 are each independently selected from a hydrogen atom, a fluorine atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group; and R 15 to R 24 are each independently selected from a hydrogen atom, a fluorine atom, a substituted or unsubstituted alkyl group, an alkoxy group, and a substituted amino group, wherein L' n is a monovalent bidentate ligand, and wherein IrL' n is represented by any one of Formulae to, where R 25 to R 39 are each independently selected from a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group; the host molecule is a hydrocarbon represented by Formula and is composed of only carbon atoms and hydrogen atoms, Ar1 - a - b - c - d - Ar6 where a, b, c, and d are each independently 0 or 1; a + b + c + d is greater than or equal to 0 and is less than or equal to 4; and Ar1 to Ar6 are each independently selected from substituted or unsubstituted benzene, substituted or unsubstituted naphthalene, substituted or unsubstituted phenanthrene, substituted or unsubstituted fluorene, substituted or unsubstituted triphenylene, substituted or unsubstituted chrysene, substituted or unsubstituted picene, substituted or unsubstituted fluoranthene, substituted or unsubstituted indeno[2,1-a]phenanthrene, and substituted or unsubstituted indeno[1,2-b]phenanthrene, where two methyl groups are located at 9-position of fluorene, 13-position of indeno[2,1-a]phenanthrene, and 12-position of indeno[1,2-b]phenanthrene; and Ar1 and Ar6 have different skeletons from each other. where Ir represents iridium; L and L' each represent a different bidentate ligand, at least one of L and L' including an alkyl group; m is 2; and n is 1, wherein IrL m is represented by Formula, where R 11 to R 14 are each independently selected from a hydrogen atom, a fluorine atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group; and R 15 to R 24 are each independently selected from a hydrogen atom, a fluorine atom, a substituted or unsubstituted alkyl group, an alkoxy group, and a substituted amino group, wherein L' n is a monovalent bidentate ligand, and wherein IrL' n is represented by any one of Formulae to, where R 25 to R 39 are each independently selected from a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group; the host molecule is a hydrocarbon represented by Formula and is composed of only carbon atoms and hydrogen atoms, Ar1 - a - b - c - d - Ar6 where a, b, c, and d are each independently 0 or 1; a + b + c + d is greater than or equal to 0 and is less than or equal to 4; and Ar1 to Ar6 are each independently selected from substituted or unsubstituted benzene, substituted or unsubstituted naphthalene, substituted or unsubstituted phenanthrene, substituted or unsubstituted fluorene, substituted or unsubstituted triphenylene, substituted or unsubstituted chrysene, substituted or unsubstituted picene, substituted or unsubstituted fluoranthene, substituted or unsubstituted indeno[2,1-a]phenanthrene, and substituted or unsubstituted indeno[1,2-b]phenanthrene, where two methyl groups are located at 9-position of fluorene, 13-position of indeno[2,1-a]phenanthrene, and 12-position of indeno[1,2-b]phenanthrene; and Ar1 and Ar6 have different skeletons from each other.