To provide an in-spindle sizing stopper whereby a sizing range of a machine can be converted without re-extraction of a stopper shaft and without lengthening a protruding amount to the rearward.

In a rear end of a spindle 1, a rotary cylinder 4 for a hydraulic chuck 2 is secured, and in a rear end of the rotary cylinder 4, a reference nut 7 is mounted through a flange 6. In the reference nut 7, a first adjusting screw 8a of an adjusting sleeve 8 is screwed capable of adjusting an axial direction position, in an internal thread 8b of the adjusting sleeve 8, a screw part 11a in a rear end of a stopper shaft 11 provided almost concentrically through a draw pipe 5 and a hollow piston 4a of the rotating cylinder 4 in a center hole of the spindle 1, is screwed capable of adjusting an axial direction position, and a sizing range is a sum of an adjusting range A of the adjusting sleeve 8 and an adjusting range B of the stopper shaft 11.