Main spindle device for machine tool

A main spindle device for a machine tool comprising a main spindle having a tip end portion to which a rotation target member is attached, the main spindle being rotatably supported to a frame so that the tip end portion becomes one end side of the frame;

• and a rotary joint configured by a distributor fixedly provided to the frame and a shaft provided to be non-rotatable to the main spindle,
• wherein the rotary joint is configured by a first rotary joint part and a second rotary joint part,
• wherein the first rotary joint part is configured by a first distributor having a shaft-shaped main body portion as a main body and a flange portion at an end portion of the main body portion, the first distributor being attached an end surface of the other end side of the frame at the flange portion in a form of the main body portion being accommodated in the frame, and a first shaft having a cylindrical shape and fitted to the main body portion, and
• wherein the second rotary joint part is configured by a second distributor having a cylindrical shape, provided to be concentrically continuous to the main body portion on an opposite side to the flange portion side in an axis line direction of the main body portion, and having an outer diameter equal to or smaller than an outer diameter of the main body portion, and a second shaft having a shaft shape to which the second distributor is fitted.