PURPOSE: To form a uniform resin film in an internal surface of a paper pipe by a relatively simplified device so as to make thickness of the resin film arbitrarily changeable without scraping off resin by a mandrel by providing a resin applying means, which applies melted resin onto the internal surface of the paper pipe, on an extension of a top end of the mandrel.

CONSTITUTION: In the cases of manufacturing a paper pipe 8, paper 3 is wound helically onto the periphery of a mandrel 1 and moved in a direction of the axial center while being rotated about the axial center. Since the paper pipe 8 is moved in the direction of the axial center while being rotated when melted resin is applied to an internal surface of the paper pipe 8 from a resin applying means 9, a resin film 14 of uniform thickness is generated in the internal surface of the paper pipe. Here, the resin applying means 9 is provided on an extension in a point end of the mandrel 1 to apply resin to an internal peripheral total surface of the paper pipe 8 by utilizing rotation and movement of the paper pipe 8, so that the resin is prevented from being scraped off by the mandrel or the like. When a supply amount of the resin and a moving speed of the paper pipe 8 are adjusted, a thickness of the resin film 14 can be easily changed.