To provide a polymer insulator with a sacrificial metal fitting capable of preventing its strength from degrading by electrolytic corrosion and improving its sealing performance even under a severe environment.

The polymer insulator 1 has a core member 2, an outer covering 5 consisting of a body part 3 and a shade 4 provided on an outer periphery of the core member 2 and a grip fitting 6 provided on the both ends of the core member 2. An end tip part 21 of the body part 3 is provided between the grip fitting 6 and the tip end part 21 of the core member 2. In the polymer insulator 1, a sacrificial metal fitting 31 is provided on an outer periphery of an opening end part 13 of the grip fitting 6 which contacts the tip end part 21 of the body 3.