PURPOSE: To improve reduction in dynamic magnification and fatigue resistance by forming a spring seat rubber of rubber in which solid spherical fly ash having specified diameters is scattered and held, which seat rubber is adapted to a suspension device for reducing oscillations and noises of an automobile.

CONSTITUTION: A spring seat rubber is adapted to a suspension device such as a strut mount for reducing oscillations and noises of an automobile. The spring seat rubber has a projection 1 and a recession 9 both formed on a surface against which a washer is abutted, an inner peripheral surface 17 formed on an inclined surface for determining a center hole, a ring-like seat part 18 formed on a back surface for receiving a coil spring. In this case, the spring seat rubber is made of rubber in which solid spherical fly ash having diameter ranging 1μm to 100μm is scattered and held. The diameters of the fly ash may range between 1μm and 20μm. The fly ash may mixed by 1 to 50wt.% in rubber of 100wt.%.