PURPOSE: To improve the yield of product by providing plural projected lines or projections in the contact part of the head at the piston-rod end of a pusher cylinder with a hollow tube stock in a pusher device for pushing the hollow tube stock between the rolling rolls of a plug mill.

CONSTITUTION: The plural projected lines 6 or projections are provided in the contact part of the head 2 at the piston-rod end of the pusher cylinder with the hollow tube stock 3. The rear end part of the hollow tube stock 3 at the time of biting the hollow tube stock 3 between the rolling rolls 4 is restrained with the plural projected lines 6 or projections which are provided on the head 2 at the piston-rod end of the pusher cylinder. Consequentely, the coefficient of friction in the contact part between the head 2 of the piston-rod end of the pusher cylinder and the hollow tube stock 3 is increased, rotation before biting the tube stock between the rolling rolls for a 2nd pass rolling or during rolling is prevented and the defects of insufficient drawing, thickness deviation in the cross section of tube, etc., resulted from deffective shape that is called as an edge-falling are prevented.