The composition of this invention is a polyethylene base resin composition containing a high concentration of an inorganic material, which has high flame retardancy and sufficient tensile elongation for practical application and is adapted to be used as a raw material for a field in which high flame retardancy is demanded such as coatings for flame retardant wires and cables and flame retardant raw material of foamed product. This composition mainly consists of a resin component formed of 10 to 75 parts by weight of polyethylene having a density ranging between 0.910 and 0.945 (g/cm.sup.3) and a melt index ranging from 0.01 to 2.0 (g/10 min) and 90 to 25 parts by weight of an ethylene-base copolymer and further contains 80 to 250 parts by weight of powder of a hydrated metal oxide on the basis of 100 parts by weight of the resin component of said polyethylene base resin composition.