A heterocyclic compound represented by the following Chemical Formula 1: wherein, in Chemical Formula 1, N-Het is a pyrimidine group unsubstituted or substituted with a phenyl group; a triazine group unsubstituted or substituted with one or more substituents selected from the group consisting of a phenyl group, a biphenyl group, a naphthyl group, a dimethylfluorene group, a dibenzofuran group and a dibenzothiophene group; a benzimidazole group unsubstituted or substituted with a phenyl group; a quinazoline group unsubstituted or substituted with one or more substituents selected from the group consisting of a phenyl group and a biphenyl group; or a phenanthroline group unsubstituted or substituted with a phenyl group, L is a direct bond; a substituted or unsubstituted arylene group; or a substituted or unsubstituted heteroarylene group, a is an integer of 1 to 3, and when a is 2 or greater, Ls are the same as or different from each other; and R1 to R10 are the same as or different from each other, and each independently selected from the group consisting of hydrogen; deuterium; halogen; a cyano group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkenyl group; a substituted or unsubstituted alkynyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted heterocycloalkyl group; a substituted or unsubstituted aryl group; a substituted or unsubstituted heteroaryl group; a substituted or unsubstituted phosphine oxide group; and a substituted or unsubstituted amine group, or two or more groups adjacent to each other bond to each other to form a substituted or unsubstituted aliphatic or aromatic hydrocarbon ring or heteroring, b and c are each an integer of 1 to 3, and when b is 2 or greater, R9s are the same as or different from each other and when c is 2 or greater, R10s are the same as or different from each other. N-Het is a pyrimidine group unsubstituted or substituted with a phenyl group; a triazine group unsubstituted or substituted with one or more substituents selected from the group consisting of a phenyl group, a biphenyl group, a naphthyl group, a dimethylfluorene group, a dibenzofuran group and a dibenzothiophene group; a benzimidazole group unsubstituted or substituted with a phenyl group; a quinazoline group unsubstituted or substituted with one or more substituents selected from the group consisting of a phenyl group and a biphenyl group; or a phenanthroline group unsubstituted or substituted with a phenyl group, L is a direct bond; a substituted or unsubstituted arylene group; or a substituted or unsubstituted heteroarylene group, a is an integer of 1 to 3, and when a is 2 or greater, Ls are the same as or different from each other; and R1 to R10 are the same as or different from each other, and each independently selected from the group consisting of hydrogen; deuterium; halogen; a cyano group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkenyl group; a substituted or unsubstituted alkynyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted heterocycloalkyl group; a substituted or unsubstituted aryl group; a substituted or unsubstituted heteroaryl group; a substituted or unsubstituted phosphine oxide group; and a substituted or unsubstituted amine group, or two or more groups adjacent to each other bond to each other to form a substituted or unsubstituted aliphatic or aromatic hydrocarbon ring or heteroring, b and c are each an integer of 1 to 3, and when b is 2 or greater, R9s are the same as or different from each other and when c is 2 or greater, R10s are the same as or different from each other. <EOS>