To provide a manufacturing method of polymer insulator tubes by which polymer tubes are manufactured through a lessened number of processes while eliminating vain use of an insulating polymer material and at the same time by which polymer tubes with improved resistance to stains are manufactured.

This manufacturing method is carried out by setting a core material in a die of a pair of die blocks 6-1, 6-2 respectively constituted of a plurality of segments 2-1, 2-2, pouring an insulating polymer material into the cavity of the die, and curing the polymer material to form an outer coating of a polymer insulator tube. In this case, shock absorbing members 11-1, 11-2 having elasticity are installed in either one or both of butting faces of the pair of the die blocks 6-1, 6-2 and then the pair of the metal blocks 6-1, 6-2 are united to give the die.