An unsaturated polyester resin composition containing 8 to 20% by weight of unsaturated polyester resin, 4 to 12% by weight of liquid thermoplastic resin, 8 to 20% by weight of glass fiber, and 50 to 75% by weight of inorganic filler, the unsaturated polyester resin containing 5.10 to 5.90 mmol/g of double bond group concentration, 1.50 to 2.50 mmol/g of ether linkage group concentration, 1.05 to 1.30 mmol/g of isopropylidene linkage group concentration, 2.50 to 3.50 mmol/g of ethylene linkage group concentration, and 3.20 to 3.60 mmol/g of methylene linkage group concentration per 1 g of unsaturated polyester.