To provide a material composition for manufacturing an electric wire having easily peeling outer coating and watertight structure by mixing a silane cross-linking agent in a resin constituent containing a specific ratio of hot-melt resin to ethylenic resin.

This watertight material composition for an electric wire is prepared by mixing a silane cross-linking agent in a resin composition including 10-50 pts.wt of hot-melt resin to 100 pts.wt of ethylenic resin. A mixing ratio of the hot-melt resin to the ethylenic resin is 10-20 pts.wt to 100 pts.wt desirably. The hot-melt resin is mixed for increasing adhesiveness of the resin constituent. As the silane cross-linking agent, vinyl alkoxy silane such as vinyl trimethoxy silane, vinyl triethoxy silane, vinyl methyldiethoxy silane, vinyl phenyldimethoxy silane, vinyl carboxy silane such as vinyl triacetoxy silane and the like are available.