A resin composition for wire coating, comprising: 100 parts by weight of a thermoplastic polyester resin (component A) having a terminal carboxyl group concentration of not more than 20 eq/ton and an intrinsic viscosity of 0.7 to 1.4 dl/g; 40 to 150 parts by weight of a polyester block copolymer (component B) obtained by carrying out a transesterification reaction between 50 to 90 wt% of a soft segment (component B-1) and 50 to 10 wt% of a hard segment (component B-2) and having an intrinsic viscosity of 0.6 to 1.1 dl/g and a melting point of 190 to 230°C, the component B-1 comprising 100 parts by mole of acid components consisting of 20 to 38 mol% of an aliphatic dicarboxylic acid component having 6 to 12 carbon atoms (component B-1-1) and 80 to 62 mol% of isophthalic acid (component B-1-2) and 100 parts by mole of an aliphatic α,ω-diol having 6 to 12 carbon atoms (component B-1-3), and the component B-2 comprising 100 parts by mole of terephthalic acid (component B-2-1) and. 100 parts by mole of an aliphatic α,ω-diol having 2 to 4 carbon atoms (component B-2-2); 0.1 to 10 parts by weight of a polycarbodiimide compound having a softening temperature of 50°C or higher (component C); 10 to 50 parts by weight of magnesium hydroxide having an average particle diameter of 0.1 to 2 μm (component D); 0.5 to 5 parts by weight of an inorganic porous filler having an average particle diameter of 0.1 to 1 μm (component E); 0.002 to 2.5 parts by weight of a hindered phenol-based antioxidant (component F); and 0.002 to 2.5 parts by weight of a phosphorus-based antioxidant (component G). 100 parts by weight of a thermoplastic polyester resin (component A) having a terminal carboxyl group concentration of not more than 20 eq/ton and an intrinsic viscosity of 0.7 to 1.4 dl/g; 40 to 150 parts by weight of a polyester block copolymer (component B) obtained by carrying out a transesterification reaction between 50 to 90 wt% of a soft segment (component B-1) and 50 to 10 wt% of a hard segment (component B-2) and having an intrinsic viscosity of 0.6 to 1.1 dl/g and a melting point of 190 to 230°C, the component B-1 comprising 100 parts by mole of acid components consisting of 20 to 38 mol% of an aliphatic dicarboxylic acid component having 6 to 12 carbon atoms (component B-1-1) and 80 to 62 mol% of isophthalic acid (component B-1-2) and 100 parts by mole of an aliphatic α,ω-diol having 6 to 12 carbon atoms (component B-1-3), and the component B-2 comprising 100 parts by mole of terephthalic acid (component B-2-1) and. 100 parts by mole of an aliphatic α,ω-diol having 2 to 4 carbon atoms (component B-2-2); the component B-1 comprising 100 parts by mole of acid components consisting of 20 to 38 mol% of an aliphatic dicarboxylic acid component having 6 to 12 carbon atoms (component B-1-1) and 80 to 62 mol% of isophthalic acid (component B-1-2) and 100 parts by mole of an aliphatic α,ω-diol having 6 to 12 carbon atoms (component B-1-3), and 100 parts by mole of acid components consisting of 20 to 38 mol% of an aliphatic dicarboxylic acid component having 6 to 12 carbon atoms (component B-1-1) and 80 to 62 mol% of isophthalic acid (component B-1-2) and 100 parts by mole of an aliphatic α,ω-diol having 6 to 12 carbon atoms (component B-1-3), and the component B-2 comprising 100 parts by mole of terephthalic acid (component B-2-1) and. 100 parts by mole of an aliphatic α,ω-diol having 2 to 4 carbon atoms (component B-2-2); 100 parts by mole of terephthalic acid (component B-2-1) and. 100 parts by mole of an aliphatic α,ω-diol having 2 to 4 carbon atoms (component B-2-2); 0.1 to 10 parts by weight of a polycarbodiimide compound having a softening temperature of 50°C or higher (component C); 10 to 50 parts by weight of magnesium hydroxide having an average particle diameter of 0.1 to 2 μm (component D); 0.5 to 5 parts by weight of an inorganic porous filler having an average particle diameter of 0.1 to 1 μm (component E); 0.002 to 2.5 parts by weight of a hindered phenol-based antioxidant (component F); and 0.002 to 2.5 parts by weight of a phosphorus-based antioxidant (component G).