Gelatin gel microcapsules with a narrow size distribution have been prepared for the use of regenerative therapy by means of SPG (Shirasu porous glass) emulsification and UV-induced cross linking, and the melting and swelling behaviors of the gel membrane of the microcapsules were observed. The gel melting temperature was proportional to the 2/3 power of UV irradiation time t for t <= 1 h and deviated from the 2/3 power behavior for t >= 1 h. The average cross-sectional area of the microcapsules that remains insoluble normalized by that at 25 degrees C monotonically increased with temperature for t <= 1 h. It then decreased, passed a minimum, and increased at high temperature for t >= 1 h. Repeated quenching of the gel microcapsules between two temperatures (25 and 40 degrees C) induced a reversible size change, which was attributed to the helix-coil transition of collagen molecules locally. From a theoretical consideration of gel particles, the observed gel melting behavior was explained well, and the scaled volume of the microcapsules was expressed as a function of scaled temperature with four fitting parameters for t <= 1 h.