Seal construction of polymer insulator

A seal construction of a polymer insulator having a core member, an outer cover member including a sheath portion and sheds, which is arranged on an outer surface of the core member, and a securing metal fitting arranged on each end of the core member, wherein a tip portion of the sheath portion is arranged between the securing metal fitting and the core member and a sealant is arranged between an inner surface of the securing metal fitting and an outer surface of the tip portion of the sheath portion, comprising:

• a small rib projecting radially outwardly from the sheath portion of the outer cover member, said small rib having a side surface connected to an open end portion of the securing metal fitting via the sealant,
• wherein the small rib does not extend radially beyond the open end portion of the securing metal fitting, and the sealant does not protrude from a portion between the side surface of the small rib and the open end portion of the securing metal fitting.