Provided is a compound of wherein: Y is O or S; X1 to X3 are each N or CH, and one or more of X1 to X3 is N; and Ar1 to Ar4 are the same as or different from each other, and each independently is an aryl group having 6 to 20 carbon atoms that is unsubstituted or substituted with nitrile or a heteroaryl group having 2 to 20 carbon atoms; or a tricyclic heteroaryl group having 2 to 20 carbon atoms that is unsubstituted or substituted with an aryl group having 6 to 20 carbon atoms, and an organic light emitting device including the same.