The invention provides a grease composition comprising a base oil consisting of a fluorinated oil and an antirust agent, wherein said antirust agent comprises an aliphatic dibasic acid salt of the formula (1) in an amount of not less than 0.1% by mass and less than 1.0% by mass based on the total mass of the grease composition: (CH2)n(COO)2Mm  (1) wherein n is an integer of 1 to 19, M is an alkali or alkaline earth metal, m is 2 when M is an alkali metal and m is 1 when M is an alkaline earth metal, and a bearing wherein the grease is packed. The grease exerts less effects on the environment. It is low in evaporation loss at a high temperature, shows good antirust property and can be suitably used in a ball bearing operated at a high temperature.