To provide a spindle mechanism capable of accelerating rapidly and rotating a rotary cup at high speed while reducing weight and size of a spindle driving part to improve maintenance efficiency.

From a driving gear 31, such as plural small-sized AC servomotors 51, or the like, disposed on an upper surface and a lower surface of a gear box 25, a driving force is transmitted to a main shaft gear 32 fixed to a main shaft 27. Thus, the small-sized AC servomotors 51 can achieve an equivalent torque with a large-sized AC servomotor by used in plural.