PURPOSE: To obtain a composition exhibiting excellent flame-retardance and high mechanical strength, etc., and free from generation of smoke and toxic gas even in a flame, by compounding a specific EVA with hydrated magnesia, red phosphorus, a hindered phenol antioxidant and an organic peroxide.

CONSTITUTION: (A) 100pts.(wt.) of an ethylene-vinyl acetate copolymer having a melt index of 1W5 and a vinyl acetate content of 10W25wt% is compounded with (B) 50W250pts. of hydrated magnesia, (C) 3W50pts. of red phosphorus, (D) 0.1W10pts. of a hindered phenol antioxidant and (E) 0.5W10pts. of an organic peroxide. The component B is preferably the one having a specific surface area of 3W15m2/g by BET method and having a content of particles of ≥5μ in diameter of 0% by the particle size distribution by Lusex method. The component C is a red phosphorus coated on the surface with a thermosetting resin having a red phosphorus content of ≥80%.