The present invention herein provides a grease composition for use in a direct acting guide apparatus, which comprises a base oil and a thickener, wherein the rate of an ester oil present in the base oil is not less than 50% by mass, the composition comprises not less than 20% by mass of the thickener which comprises a compound having a terminal aliphatic hydrocarbon group and free of metal and it has a penetration ranging from 220 to 300, as well as a direct acting guide apparatus which comprises the foregoing grease composition. The grease composition of the present invention has various excellent characteristic properties such that it generates only a small quantity of dust, that the production cost thereof is low, that the composition is free of metallic component and that it is free of bad roll feeling.