To provide a lubricant composition which maintains noise reduction effectiveness over a long period of time when it is used for the lubricity of an intermeshing part between rollingly contact gears.

The lubricant composition is filled into a region including an intermeshing part of a drive gear 21 and a driven gear 22 of a reduction gear 19. The lubricant composition comprises a lubricating oil as a lubricant and shock absorber particles having an average particle size of 300-500 m. An average particle size of 300 m or more provides marked effectiveness in reducing sliding sound. On the other hand, tooth hitting noise of the gears increases as the average particle size of the shock absorber particles is increased. Therefore, the average particle size of the shock absorber particles has been established in the above range.