A method for producing 2-hydroxyethyl methacrylate polymers comprising polymerizing 2-hydroxyethyl methacrylate or a monomer mixture thereof containing a halogen compound thorough radical polymerization; method for producing hydrogels comprising subjecting the polymers to a water-imparting treatment; method for producing water-containing soft contact lenses comprising molding the polymers into a shape of contact lens and subjecting them to a water-imparting treatment and method for producing polymers comprising treating at least molding surfaces of molds, which form a cavity of contact lens shape, with a halogen compound and polymerizing 2-hydroxyethyl methacrylate or a monomer mixture thereof in the cavity through radical polymerization are disclosed. According to the present invention, water-containing soft contact lenses with high heat resistance and intermediates therefor are obtained from 2-hydroxyethyl methacrylate of high purity.