PURPOSE: To prevent mouthpiece deforamtion and perform smooth winding and feeding operations by forming outer end of the mouthpiece funnel-like so that when the mouthpiece is fitted over a collar the collar contacts part of the mouthpiece slightly inner than the outer end.

CONSTITUTION: A mouthpiece, for being inserted and fixed into and reinforcing a paper pipe 11, is formed so that the outer end 15 of a cylindrical body 13 is funnel-like with an opening angle α slightly greater than an opening angle βof a collar 16. When both ends of the core pipe are fitted over the collars 16's, an innermos part of the funnel-shaped part 15 of the mouthpiece 12 comes in contact with the collar 16. Then the part of the paper pipe 11 in contact with the collar becomes to have longer life than when external forces are applied to the outer end periphery, producing less deformation against external forces. Accordingly, the mouthpiece 12 has greater apparent strength, leading to smoother roll paper winding and feeding operations with improved operation efficiency.