entering the first and the second cylinders 25 26 the neck opening fixation plates 20 22 are thus pushed outward by means of spring force and stopped by respective check blocks to stretch the neck opening of the shirt the front end of each said neck opening fixation plate 20 22 is arranged in a curved shape to match with the neck opening and the rear end of each said neck opening fixation plate is arranged to provide a curved slot 27 28 by means of a bolt 29 through the curved slot 27 28 each neck opening fixation plate 20 22 is tightly screwed up with respective matching plate 14 16 such that the contained angle between the matching plate and the neck opening fixation plate is adjustable to fit all styles of neck openings the check blocks 30 32 which are arranged to confine the stroke of the neck opening fixation plates 20 22 are threaded by a screw 34 and arranged at both ends of the screw 34 the central part of the screw 34 is a smooth portion 36 and the bilateral threads have a same pitch and are arranged in reverse direction therefore when the operator turns the revolving button 38 which is tightly mounted on the screw 34 the check blocks 30 32 will be driven to move relatively and the distance between the check blocks 30 32 will be adjusted accordingly when the distance between said two check blocks 30 32.