Adsorption and desorption of a hydrophobic organic molecule onto N-isopropylacrylamide gel (thermosensitive polymer gel) undergoing hydrophobic-hydrophilic balance change were performed. The time courses of the adsorption (desorption) under a variety of heating (cooling) rates are elucidated. from which the adsorption mechanism of the hydrophobic organic molecule onto the gel is analyzed kinetically using theoretical models of adsorption process including rate determining step. The rate of adsorption is controlled by film diffusion of the adsorbate. Adsorption occurs on the surface of the gel.