PURPOSE: To enhance the impact resistance of a blend of polymers by making the bland contain a specific fluorine-containing polymer and a core-shell polymer having a shell composed of a monomer such as a vinyl aromatic monomer.

CONSTITUTION: A vinyl aromatic monomer or (cyclo)alkyl methacrylate (e.g.; methyl methacrylate) (ii) is polymerized in the presence of a core polymer composed of a rubbery polymer being a polymer of a monomer pref. composed of butadiene or 3-8C alkyl acrylate (e.g.; n-butyl acrylate (i) to obtain a core- shell polymer (b) having a shell composed of the monomer of the component (ii). A fluorine-containing polymer composed of a monomer represented by formula (wherein one or more of A, B, D and E is H, one or more of them is F and the remainder two are H and F) pref. being a polyvinylidene fluoride (a) is mixed with 50 wt.% or less, pref. 8-15 wt.% of the component (b) as an impact modifier.