A grease composition that is suitable for use in a rolling bearing exposed to high temperature and that exhibits stable lubricity for a prolonged period of time; and a bearing having the same sealed therein. There is provided a grease composition comprising (a) base oil, (b) thickening agent, (c) any of alkylthiocarbamoyl having compounds of the general formula (1): (1) (wherein each of R1, R2, R3 and R4 independently is a C1-C20 alkyl, and X is S, S-S, S-CH2-S, S-CH2CH2-S or S-CH2CH2CH2-S) and (d) amine-ketone condensate antioxidant. Further, the grease composition may contain (e) metal inactivator.