Double network (DN) gels are anomalously robust but soft and wet materials, whose maximum stress in compression reaches 30MPa and surface friction coefficient reaches 0.001 simultaneously. The DN gels also have shock absorbency, permeability, and biocompatibility. Thus it is expected that the DN gels will be applied to artificial joints, artificial cartilages, and artificial blood vessels. In this study we focused on both high transparency and large transformation of the DN gels, and we tried to develop novel optical devices. Our purpose is to apply it to a deformable lens system. Indeed, we succeed to make an artificial gel lens, which is nontoxic and have biocompatibility. The value of strain of the gel lens can achieve more than 2, and Young's moduli of our two kinds of DN gels show 0.45MPa and 0.46×10^-1MPa, which is enough higher than human lens. We will realize further miniaturization and simplification of various optical products containing the gel lens.