A flame-retardant olefin polymer composition superior in surface whitening preventing property is obtained by blending 100 parts by weight of a resin component consisting principally of:a) 99-60% by weight of a polyolefin resin andb) 1-40% by weight of an olefin polymer modified with an unsaturated carboxylic acid or a derivative thereof: withc) 5-200 parts by weight of a flame retardant: andd) at least one component selected from the group consisting of:1 a mineral oil, a wax, or a paraffin.2 a higher fatty acid or an ester, amide or metallic salt thereof,3 a silicone4 a partial fatty ester of a polyhydric alcohol or aliphatic alcohol-, fatty acid-, aliphatic amino-, fatty acid amide-, alkylphenol- or alkylnaphthol-ethylene oxide adduct, and5 a fluoric elastomer.