Lubricant composition and an electric power steering apparatus using the speed reducer and it using the same

The lubricant base oil, and fine particles, and a lubricant composition containing a calcium sulfonate-based thickener, a reduction gear filled with the lubricant composition, in the electric power steering apparatus incorporating the reduction gear there are, while preventing oil separation under the action of calcium sulfonate-based thickener added to the lubricant composition, by the action of fine particles, noise reducer, a combination of a small gear and a large gear regardless of the size of the backlash of time, and without complicating the structure of the reduction gear, since it smaller than ever, possible to reduce noise in the cabin caused by the electric power steering apparatus cost low cost can.