There are provided a radiation-proof resin composition that is excellent in mechanical characteristics even after exposure to harsh radiation (with 2.5 MGy), that exhibits a suitable radiation-resistant properties by a small amount of mixed additives, and that can suppress the blooming of the additives, and a radiation-resistant wire/cable. The radiation-resistant resin composition is obtained by adding 0.3 to 1.0 parts by mass of a salicylate-based UV absorber, 0.3 to 5 parts by mass of a benzotriazole-based UV absorber, and 0.3 to 5 parts by mass of a triazine-based UV absorber to 100 parts by mass of a polyolefin-based resin.