A method for manufacturing a bladder for use in manufacturing tires having a surface-modified rubber layer on an outer surface side of a base rubber layer, including the steps of: forming an uncross-linked body of the surface-modified rubber layer by molding a rubber composition including a modified butyl rubber composition and an organic peroxide and applying a siloxane compound having a (meth)acryloyl group to a surface of this rubber molded body; forming the base rubber layer from an unvulcanized body or vulcanized body formed from a rubber composition different than the modified butyl rubber composition; laminating the uncross-linked body of the surface-modified rubber layer on the outer surface side of the base rubber layer; and heat treating.