A nitrogen-containing heterocyclic compound represented by the following formula 1: wherein X is C or Si; one or more of R 1 to R 5 are each independently represented by -L-A, wherein L is a direct bond or a divalent group containing one or more selected from the group consisting of a substituted or unsubstituted aromatic ring group and a substituted or unsubstituted heterocyclic group, and A is selected from the group consisting of a substituted or unsubstituted terphenyl group, a substituted or unsubstituted triphenylene group, a substituted or unsubstituted phenanthroline group, a substituted or unsubstituted fluoranthene group, a substituted or unsubstituted fluorene group, a substituted or unsubstituted quinazoline group, a benzimidazole group substituted with an alkyl group, a substituted or unsubstituted dibenzothiophene group, and a substituted or unsubstituted dibenzofuran group; the remainder of R 1 to R 5 are selected from the group consisting of hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkylthioxy group, a substituted or unsubstituted arylthioxy group, a substituted or unsubstituted alkylsulfoxy group, a substituted or unsubstituted arylsulfoxy group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted boron group, a substituted or unsubstituted alkylamine group, a substituted or unsubstituted aralkylamine group, a substituted or unsubstituted arylamine group, a substituted or unsubstituted heteroarylamine group, a substituted or unsubstituted aryl group, a substituted or unsubstituted fluorene group, a substituted or unsubstituted carbazole group, and a substituted or unsubstituted heterocyclic group containing at least one heteroatom selected from N, O and S; a, b, d and e are each independently an integer ranging from 1 to 4; and c is an integer ranging from 1 to 3. X is C or Si; one or more of R 1 to R 5 are each independently represented by -L-A, wherein L is a direct bond or a divalent group containing one or more selected from the group consisting of a substituted or unsubstituted aromatic ring group and a substituted or unsubstituted heterocyclic group, and A is selected from the group consisting of a substituted or unsubstituted terphenyl group, a substituted or unsubstituted triphenylene group, a substituted or unsubstituted phenanthroline group, a substituted or unsubstituted fluoranthene group, a substituted or unsubstituted fluorene group, a substituted or unsubstituted quinazoline group, a benzimidazole group substituted with an alkyl group, a substituted or unsubstituted dibenzothiophene group, and a substituted or unsubstituted dibenzofuran group; the remainder of R 1 to R 5 are selected from the group consisting of hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkylthioxy group, a substituted or unsubstituted arylthioxy group, a substituted or unsubstituted alkylsulfoxy group, a substituted or unsubstituted arylsulfoxy group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted boron group, a substituted or unsubstituted alkylamine group, a substituted or unsubstituted aralkylamine group, a substituted or unsubstituted arylamine group, a substituted or unsubstituted heteroarylamine group, a substituted or unsubstituted aryl group, a substituted or unsubstituted fluorene group, a substituted or unsubstituted carbazole group, and a substituted or unsubstituted heterocyclic group containing at least one heteroatom selected from N, O and S; a, b, d and e are each independently an integer ranging from 1 to 4; and c is an integer ranging from 1 to 3.