A halogen-free flame-retardant resin composition includes a polyolefin-based resin, a phenolic antioxidant, a metal hydroxide, a pigment comprising one of titanium dioxide, monoazo yellow, benzimidazolone yellow, isoindolinone yellow, quinacridone red and perylene red, and an additive including an amide bond. The additive having the amide bond is added in an amount of 0.01 to 2 parts by weight relative to 100 parts by weight of the polyolefin-based resin.