RESIN COMPOSITION

PROBLEM TO BE SOLVED: To obtain a resin composition which has improved flowability and can give a molding having uniform appearance and improved weld strength, heat resistance and heat stability by mixing an aromatic polysulfone resin with a specified copolymer. SOLUTION: At least one aromatic vinyl monomer selected from among styrene, α-methylstyrene, p-t-butylstyrene, vinyltoluene and p-chlorostyrene in an amount of 1-99 pts.mol. is copolymerized with 99-1 pts.mol. maleimide monomer represented by formula I (where R is H or Cn H2n+1 ((n) is 1-4), a group of formula II or a group of formula III; P1 and P2 are each H, CH3 , C6 H5 , OH, OCH3 , Cl or COOH) and 0.01-20 pts.mol., per 100 pts.mol. of the total of these monomers, at least one organic acid anhydride monomer selected from among maleic anhydride, phthalic anhydride, fumaric anhydride, itaconic anhydride, etc., to obtain a copolymer having a weight-average molecular weight of 10,000-300,000. This copolymer of 1-40 pts.wt. is mixed with 99-60 pts.wt. aromatic polysulfone resin having a weight-average molecular weight of 10,000-50,000.