To provide a tapered composite insulator and a molding method for its covering, enabling a die cost to be reduced and hence enabling the overall cost to be reduced.

A polymer bushing 1 comprises a core member 2 and a covering 3 consisting of a trunk part 4 provided on the periphery of the core member 2 and plurality of sheds 5, and also has straight parts S of fixed diameters and tapered parts T having gradually decreasing diameters and connected with continuity to the straight parts S. An index point 11 in the covering 3 at which the straight part S turns into the tapered part T is set up to be biased to the tapered part T side relative to an index point 12 in the core member 2 at which the straight part S turns into the tapered part T. Prior to molding the covering, when the core member 2 is set on a die used molding the covering, the index point 11 at which segments in the die for molding the straight part S of the covering 3 turn into segments for molding the tapered part T thereof is set up to be biased to the tapered part T side relative the index point 12 in the core member 2 at which the straight part 2 turns into the tapered part T.