To provide a polymer insulator and a manufacturing method thereof which can attain cost reduction for the whole insulator and visual discrimination of erosion development in a preferable embodiment.

This polymer insulator 1 consists of a core member 2, and a covering 3 made of insulating macromolecular material formed at the outer periphery of the core member 2, whereas the covering 3 consists of a sheath part 4 covering the outer periphery of the core member 2, and a plurality of sheds 5 which are formed at an appropriate interval in longitudinal direction and extend radially outward from the outer periphery of the sheath part. The covering 3 is formed into a two-layered structure of a surface layer part 3-1 and any inner layer part 3-2 other than the surface layer part, the surface layer part is constituted of rubber indicating high water repellency, consisting of silicone rubber or fluororubber, and the inner layer part is constituted of any rubber other than the silicone rubber and the fluororubber. As a preferable embodiment, the thickness of the surface layer part is formed so as to be 1 mm or larger to make the colors of the surface layer part and the inner layer part different from each other.