The present invention addresses a problem of providing a grease composition containing a urea-based thickener and capable of appropriately maintaining the kinematic friction force in lubrication parts. The grease composition contains a base oil (A) and a urea-based thickener (B), wherein the base oil (A) has a kinematic viscosity at 40° C. of 100 mm2/s or more, and the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.