PURPOSE: The titled composition having improved compatibility, provided with the characteristics of epoxy resin, capable of effecting the water proofing and anticorrosion of hermetically closed parts, obtained by blending cut-back asphalt with emulsion type rubber, epoxy resin, its curing agent and water.

CONSTITUTION: 100pts.wt. Cut-bacl asphalt in high-temperature state (50W80°C) is fully blended with 50W100pts.wt. curing agent for epoxy resin in high-temperature state (50W60°C) and 60W90pts.wt. emulsion type rubber (preferably styrene- butadiene type rubber having concentration 40W50wt%, etc.) to give a solution, which is blended with 50W100pts.wt. epoxy resin solution (e.g., glycidyl ether type, etc.) and ≤30pts.wt. water based on total amount of composition when it is required. The addition of an ultraviolet light absorber improves further weather resistance.