PURPOSE: To obtain a miscible blend excellent in mechanical properties such as elastic modulus by blending a polycarbonate resin, a thermoplastic copolymer of styrene series monomer and acrylonitrile series monomer and a polysulfone- carbonate copolymer.

CONSTITUTION: (A) 1 to 100 pts.wt. the polycarbonate resin induced from, for example, 2,2-bis-(4-hydroxyphenyl)propane and a carbonate precursor such as di(halophenyl)carbonate and carbonyl halide and (B) 1 to 100 pts.wt. the thermoplastic copolymer of styrene series monomer such as (α-methyl)styrene and acrylonitrile series monomer such as (substituted)acrylonitrile are blended with (C) miscible effective amount of the polysulfone-carbonate copolymer obtained by polymerization of sulfone-containing bisphenol (e.g. xylenolsulfone) and the carbonate precursor.