Provided are anthracene derivatives of Chemical Formula 1: wherein: X1 is O or S; R1 and R2 are the same as or different from each other, and each independently is hydrogen, deuterium, a nitrile group, a halogen groups a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, or bond to adjacent groups to form a substituted or unsubstituted ring; Ar is a substituted or unsubstituted heteroaryl group comprising O or S; and a is an integer of 0 to 9, and b is an integer of 0 to 8, and when a is 2 or greater, R1s are the same as or different from each other, and when b is 2 or greater, R2s are the same as or different from each other. Also provided are organic light emitting devices comprising same.