Polyvinyl chloride resin composition

A polyvinyl chloride resin composition having a high falling weight impact resistance, stress-whitening resistance and optical characteristics, comprising:

• 100 parts by weight of a polyvinyl chloride resin and
• 2 to 40 parts by weight of a multi-stage copolymer obtained by polymerizing resin component formable monomers in the range of from more than 30 parts by weight to 50 parts by weight, said resin component formable monomer being composed of 25 to 55% by weight of methyl methacrylate, 2 to 15% by weight of an alkyl acrylate having a C.sub.1 -C.sub.8 alkyl group and 30 to 60% by weight of an aromatic vinyl monomer in the presence of from 50 parts by weight to less than 70 parts by weight of a butadiene elastomer having a glass transition temperature of from -40.degree. C. to 5.degree. C. obtained by copolymerization of a monomer mixture of 70 to 90% by weight of butadiene, 10 to 30% by weight of an aromatic vinyl monomer and a polyfunctional monomer added in an amount corresponding to 3 to 10 parts by weight per 100 parts by weight of total amount of said butadiene and aromatic vinyl monomer, wherein a polymerization of the resin component formable monomer is conducted by polymerizing in the first stage methyl methacrylate in an amount corresponding to 45 to 85% by weight of the total amount of methyl methacrylate and the alkyl acrylate in an amount in the range specified above, subsequently polymerizing in the second stage the aromatic vinyl monomer in an amount in the range specified above in the presence of the polymer obtained in the previous stage, and further polymerizing in the third stage the remainder of methyl methacrylate in the presence of the polymers obtained in said first and second stages.