The invention provides a novel process for producing fluoropolymers, specifically, a process for producing photoresist fluoropolymers which are transparent to vacuum ultraviolet rays, particularly, F2 laser (157nm), and excellent in solubility in alkaline developers; and photoresist compositions containing the photoresist fluoropolymers. The process is a process for producing a resist fluoropolymer excellent in solubility in developers which comprises repeating units (M2)of alicyclic structure in the backbone chain and has in the polymer either acid-reactive groups (Y1) or groups (Y2) convertible into acid-reactive groups (Y1), characterized by radical-polymerizing a monomer mixture containing a monomer (m2) capable of imparting alicyclic structure to the backbone chain in the presence of both a radical polymerization initiator and a chain transfer agent represented by the general formula (1): R - (X)n (1), in which R is a C1-20 hydrocarbon group optionally containing an ether linkage in which part of the hydrogen atoms may be replaced by fluorine; X is at least one functional group selected from the group consisting of oxygen-containing functional groups and substituted and unsubstituted amino groups; and n is an integer of 1 to 4.