A nitrogen-containing compound represented by Formula 1 below: wherein in Formula 1, X 1 to X 13 are each independently CR 1, CR 2 or N, at least one of X 1 to X 8 and at least one of X 9 to X 13 are N, R 1 is selected from hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, at least one of X 1 to X 13 is CR 2, and R 2 is represented by Formula 2 below: wherein in Formula 2, Q1 is CY 1 Y 2, SiY 3 Y 4, NY 5, O or S, R 3, R 4 and Y 1 to Y 5 are each independently selected from hydrogen, deuterium, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, Y 1 and Y 2, and Y 3 and Y 4 optionally combine with each other to form a hydrocarbon ring or heterocycle, and a and b are each independently an integer of 1 to 4; wherein: Formula 1 is represented by Formulae 1-1 or 1-2 below: wherein in Formulae 1-1 and 1-2, X 1 to X 13, and R 2 are the same as defined in Formula 1; or wherein Formula 1 is represented by Formulae 1-3-1 or 1-4-1 below: wherein in Formulae 1-3-1 and 1-4-1, X 5 is CH or N, and X 9 to X 13, and R 2 are the same as defined in Formula 1; or wherein Formula 1 is represented by Formulae 1-3-2 or 1-4-2 below: wherein in Formulae 1-3-2 and 1-4-2, X 12 is CH or N, and X 1 to X 8, and R 2 are the same as defined in Formula 1. X 1 to X 13 are each independently CR 1, CR 2 or N, at least one of X 1 to X 8 and at least one of X 9 to X 13 are N, R 1 is selected from hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, at least one of X 1 to X 13 is CR 2, and R 2 is represented by Formula 2 below: wherein in Formula 2, Q1 is CY 1 Y 2, SiY 3 Y 4, NY 5, O or S, R 3, R 4 and Y 1 to Y 5 are each independently selected from hydrogen, deuterium, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, Y 1 and Y 2, and Y 3 and Y 4 optionally combine with each other to form a hydrocarbon ring or heterocycle, and a and b are each independently an integer of 1 to 4; Q1 is CY 1 Y 2, SiY 3 Y 4, NY 5, O or S, R 3, R 4 and Y 1 to Y 5 are each independently selected from hydrogen, deuterium, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, Y 1 and Y 2, and Y 3 and Y 4 optionally combine with each other to form a hydrocarbon ring or heterocycle, and a and b are each independently an integer of 1 to 4; wherein: Formula 1 is represented by Formulae 1-1 or 1-2 below: wherein in Formulae 1-1 and 1-2, X 1 to X 13, and R 2 are the same as defined in Formula 1; or wherein Formula 1 is represented by Formulae 1-3-1 or 1-4-1 below: wherein in Formulae 1-3-1 and 1-4-1, X 5 is CH or N, and X 9 to X 13, and R 2 are the same as defined in Formula 1; or wherein Formula 1 is represented by Formulae 1-3-2 or 1-4-2 below: wherein in Formulae 1-3-2 and 1-4-2, X 12 is CH or N, and X 1 to X 8, and R 2 are the same as defined in Formula 1. Formula 1 is represented by Formulae 1-1 or 1-2 below: wherein in Formulae 1-1 and 1-2, X 1 to X 13, and R 2 are the same as defined in Formula 1; or wherein Formula 1 is represented by Formulae 1-3-1 or 1-4-1 below: wherein in Formulae 1-3-1 and 1-4-1, X 5 is CH or N, and X 9 to X 13, and R 2 are the same as defined in Formula 1; or X 5 is CH or N, and X 9 to X 13, and R 2 are the same as defined in Formula 1; or wherein Formula 1 is represented by Formulae 1-3-2 or 1-4-2 below: wherein in Formulae 1-3-2 and 1-4-2, X 12 is CH or N, and X 1 to X 8, and R 2 are the same as defined in Formula 1. X 12 is CH or N, and X 1 to X 8, and R 2 are the same as defined in Formula 1.