The present invention provides a polymer gel composition including: at least two polymer compounds which interact with each other to form a polymer complex; and a liquid. One of the polymer compounds forms a three-dimensional crosslinked structure, at least one other polymer compound is compatible with the liquid, and at least a portion of the compatible polymer compound is included in the three-dimensional crosslinked structure. Preferably, when the polymer complex is disassembled or decomposed by stimuli, the polymer compound forming the three-dimensional crosslinked structure changes its volume by absorbing or releasing the liquid. The three-dimensional crosslinked structure is preferably in a particle shape. An optical device using such a polymer gel composition is also provided.