<；P>；PROBLEM TO BE SOLVED: To provide a block polymer which is industrially advantageously produced in a simple process at low cost, and to provide a cosmetic composition which contains the block polymer and is excellent in curl retention, flexibility, non tackiness, non flaking, and silicone oil dispersion stability as, for example, hair set agent compositions. <；P>；SOLUTION: A silicone block polymer is provided which includes a polysiloxane block and two or more blocks composed of a monomer having a vinyl-based functional group. The two or more blocks composed of the monomer having the vinyl-based functional group are linked via a linkage monomer having a radical-polymerizable vinyl-based functional group and a non-radical-polymerizable functional group. <；P>；COPYRIGHT: (C)2010,JPO&INPIT
