A polymerization device that includes: a reaction vessel that houses a polymerization solution and in which a polymerization reaction is performed; a stirring blade that stirs the polymerization solution housed in the reaction vessel; a plurality of heat transfer pipes that transfer heat to the polymerization solution in order to start the polymerization reaction and cause the polymerization reaction to proceed, and that remove, from the polymerization solution, heat generated by the polymerization reaction; and a baffle arranged between a vessel wall of the reaction vessel and the heat transfer pipes.