To control the microstructure and the responsive rates of hydrogels, a temperature-induced phase separation (TIPS) method applied to an organic-inorganic hybrid hydrogel. A copolymer between thermosensitive poly(N-isopropylacrylamide), polyNIPA, and a vinyl monomer possessing a trimethoxysilyl group was synthesized by radical reaction. Its cross-linking could be carried out by hydrolytic polycondensation of trimethoxysilyl groups. During both reactions, the pre-gel solution was separated into two phases by heating above a lower critical solution temperature of the elongating polyNIPA copolymer. The responsive rates of the microporous gel could be controlled by characteristic diffusion path length as the thickness of micropore wall, instead of the macroscopic sample size. Therefore, the shrinking rates of the hydrogel could be successfully maximized by fixing the phase-separated, microporous polymer network. Besides the interconnectivity of generated pores, the thermally triggered shrinking kinetics was investigated.