Abstract: An apparatus for manufacturing a resin tube comprising: (a) a support means; (b) a central support by the support means and extending therefrom; (c) a pair of operating means supported by the central shaft at two separate positions; (d) a plurality of rotatable forming rolls each supported by the operating means at both ends thereof in such a manner that the rotatable forming rolls are arranged circularly around the central shaft and that a cylindrical envelope formed by the rotatable forming rolls has a radius changeable by operation of the operating means; and (e) a plurality of flexible link means each connected between one end of each rotatable forming roll and a driving means for simultaneously rotating the rotatable forming rolls in the same direction at any radius of the envelope. Because of this structure, the apparatus can manufacture a resin tube of any size simply by operating the operating means.