Abstract: The present invention relates to the trail spindle of a lathe including an oil hydraulic circuit for thrust compensation, wherein lathe turning operations on a processing object can be performed always accurately by preventing the processing object from being swung and the shape of the processing object from being deformed, in such a manner that necessary thrust is generated by using an oil hydraulic cylinder and a pressure reducing and relieving valve without using the existing method of moving a tail spindle using a screw and the oil hydraulic circuit automatically performs thrust compensation (i.e., maintains constant thrust) according to a change in the length of the processing object during lathe turning operations.