PURPOSE: To polymerize α,β-unsatd. compds. by a base transfer polymn. method by using perfluorocarbanion salts having a specific constitutional formula as a catalyst.

CONSTITUTION: The α,β-unsatd. compds. are polymerized under the base transfer polymn. conditions by using the tris(disubstituted amino)sulfonium perfluorocarbanion salt expressed by formula I as the catalyst. In the formula I, R1 to R6 are respectively independently selected and are each 1-20C alkyl having at least two α hydrogen atoms or any or all of paired R1 and R2, R3 and R4 as well as R5 and R6 are respectively independently selected and are each formula II or formula III, where Y is hydrogen or methyl; R, R and R are respectively independently selected, and are each F, 1-20C perfluoroalkyl or the like R is 1-20 perfluoroalkyl, or the like; or any one or paired R and R and R and R, R and R as well as R and R is together formula IV, where (n)is an integer from 2 to 6; each of paired R and R and R and R, or each of R and R and R and R is together the formula IV and (n) is the integer from 2 to 6.