The invention provides a lubricating grease composition with a worked penetration of 400 to 500 for a machine tool equipped with an automatic lubricator, containing a base oil having a kinematic viscosity at 40° C. of 10 to 200 mm2/s and 0.1 to 10 mass % of solid particles insoluble in the base oil. The lubricating grease composition of the invention can be fed using the automatic lubricator attached to the machine tool, and can prevent the stick-slip from occurring on the sliding lubrication portion of the machine tool.