The invention provides a grease composition suitable for being packed in roll bearings to be lubricated at elevated temperatures and a bearing in which the above-mentioned grease composition is packed. In the grease composition containing a base oil, a urea-containing thickener and an additive, the additive includes an overbased metal sulfonate and the amount of the overbased metal sulfonate is 0.05 to 1.00 mass % with respect to the total amount of the grease composition. The bearing has the above-mentioned grease composition sealed therein.