PURPOSE: To obtain a lightweight insulating polymeric material composition capable of enhancing weather and tracking resistance of a polymeric insulating material using a resin material.

CONSTITUTION: This insulating polymeric material composition for outdoor use is obtained by selecting an ethylene propylene diene monomer rubber (EPDM rubber) as a polymeric material, simultaneously adding aluminum hydroxide and carbon black as a filler to the EPDM rubber and molding the resultant ternary kneaded mixture with an injection molding means. General-purpose carbon black having 2.8 ratio of specific surface area/particle diameter and 0.6% volatile content, 1.5 ratio of specific surface area/particle diameter and 0.7% volatile content, 1.4 ratio of specific surface area/particle diameter and 0.4% volatile content, 0.3 ratio of specific surface area/particle diameter and 0.6% volatile content or 0.3 ratio of specific surface area/particle diameter and 0.4% volatile content produced by a furnace method is adopted as the carbon black.