PURPOSE:To prepare a compsn. which generates little odorous component, is excellent in the heat stability, and is suitable as packaging material for a liq. food or drink by mixing an alkali metal acetate and phosphoric acid or an alkali metal hydrogenphosphate each in a specified amt. into a saponified ethylene-vinyl acetate copolymer. CONSTITUTION:An alkali metal acetate in an amt. corresponding to 20 to 200ppm said alkali metal, 30 to 250ppm acetic acid, and phosphoric acid or an alkali metal hydrogenphosphate in an amt. corresponding to 5 to 500ppm phosphoric acid are mixed into a saponified ethylene-vinyl acetate copolymer in such a way that the ratio of the content of said acetic acid to the content of the acetic acid combined with said alkali metal acetate is 0.1-1, thus giving a compsn. which has an ethylene content of 20 to 80mol% and a degree of saponification of vinyl acetate units of 95mol% or higher, and which, when tested with a Koka flow tester, exhibits a flow rate remaining substantially unchanged for at least 10hr during heating at least at a temp. in the range of 10-80 deg.C higher than its m.p.