The sorption of rhodamine 6G into single silica gel micro-particles possessing pore sizes of 3, 61 15, and 30 nm was analyzed using single microparticle injection and microabsorption methods. The intraparticle diffusion of the solute was highly influenced by the pore size of the silica gel. The relationship between the intraparticle diffusion coefficient and a hindrance parameter for the diffusion in the pores is discussed on the basis of a pore and surface diffusion model.