Patent ID: 7910525

Claim:
A grease composition comprising a base grease consisting of a base oil and a thickener; and an additive added to said base grease, wherein said additive comprises a bismuth-based additive, wherein a mixing ratio of said bismuth-based additive is set to 0.01 to 15 parts by weight for 100 parts by weight of said base grease, wherein said bismuth-based additive consists of at least one additive selected from the group consisting of bismuth powder and sodium bismuthate, wherein an average particle diameter of said bismuth powder is 10 to 200 μm, wherein said base oil consists of at least one oil selected from the group consisting of alkyldiphenylether oil, poly-α-olefin oil, mineral oil, ester oil, and ether oil, wherein said thickener is a diurea-based compound represented by a formula (1): R 1 and R 3 in said formula (1) indicates hydrocarbon radicals having 6 to 20 carbon atoms; R 1 and R 3 may be identical to or different from each other; R 2 indicates an aromatic hydrocarbon radical having 6 to 15 carbon atoms.