PURPOSE: To obtain a modified polytetrafluoroethylene fine powder being a bright transparent material suitable for surface coating containing a repeating unit based on a tetrafluoroethylene monomer and a dioxole monomer and consisting of a core part and a shell part and produced by a dispersion polymerization method.

CONSTITUTION: A modified polytetrafluoroethylene fine powder compsn. consists of a core part containing a copolymer consisting of a repeating unit based on a monomer A and a repeating unit based on a monomer B and a shell part not containing a repeating unit substantially based on the monomer B and is produced by a dispersion polymerization method. The monomer (A) is a tetrafluoroethylene monomer and the monomer (B) is a dioxole monomer represented by formula I [wherein X and X' are selected from the group consisting of F, Cl and H and Y is a group represented by formula II (wherein Z and Z' are selected from the group consisting of F, 1-6C alkyl and 1-6C fluorinated alkyl].