PURPOSE: To manufacture the titled cylindrical body excellent in wall surface buckling strength by setting in a mold an uncured FRP tube that a heating foam is inserted in and heating, expanding it to mold a tube.

CONSTITUTION: Heating foaming resin (such as polyethylene foam) 5 having a suitable length and shape is inserted into an uncured FRP tube 4 impregnated with resin and set in molds 3. After the molds are clamped, the resin 5 is heated and expanded and the tube 4 is pushed by this foaming pressure to the molds and cured to obtain a cylindrical body with a desired foam. Hereby, when the foaming resin 5 is tried not to be inserted into the end of the tube, sealing can be conducted relatively easily.