PURPOSE: To produce a plastic pipe having memory property such that it increase a pipe diameter at the time of heating.

CONSTITUTION: A worn-out pipeline is often lined with a plastic pipe having a memory property expanding the pipe at the time of heating. This memory property is achieved by generating crosslinking reaction in a plastic material 4 in a pipe molding means 1 and subsequently moving the plastic pipe yet held to a hot state through a shrink mold 5. When the pipe 16 is yet in a plastic state, in a desired case, the pipe can be corrugated in the corrugating machine 8 positioned behind the shrink mold 5.