Abstract: A methacrylic acid ester composition comprising 10 to 50 parts by weight of a cross-linked acrylic acid ester elastomer (A) and 50 to 90 parts by weight of a resin component, the total amount of the elastomer (A) and the resin component being 100 parts by weight; which is prepared by(a) preparing the cross-linked acrylic acid ester elastomer (A) by emulsion-polymerization,(b) adding a monomer component (B) to the elastomer (A) in the emulsion, and(c) polymerizing a monomer mixture (2) in the presence of the elastomer (A) to give the resin component.The composition is excellent in the processibility and can provide the film having the excellent transparency, weatherability, flexbility and whitening resistance to hot water.