Polymers of high oxygen permeability and a low modulus of elasticity and ophthalmic lenses and contact lenses using the same are provided. The polymers are characterized in that they are obtained by copolymerizing 5 to 90 parts by weight of a monomer (SiMAA) represented by the formula below, 5 to 90 parts by weight of 3-tris (trimethylsiloxy) silyl propyl methacrylate (TRIS), 5 to 70 parts by weight of N,N-dimethyl acrylamide (DMAA) and 0.1 to 3 parts by weight of monomer having two or more copolymerizable carbon-carbon unsaturated bonds in 1 molecule (provided that the total quantity of SiMAA, TRIS and DMAA is 100 parts by weight and that the total quantity of SiMAA and TRIS is 30 to 95 parts by weight), and which are used for ophthalmic lenses.