We have synthesized minute SiC products from polyvinylsilane (PVS), which is a liquid organosilicon polymer, with radiation curing. Since there is a close relationship between the properties of obtained SiC products and pyrolysis condition, it is important to investigate the ceramization process of cured PVS in order to find out the optimum pyrolysis condition. In this paper, the ceramization process of the PVS cured by gamma-ray irradiation at room temperature was investigated by gas analysis, thermogravimetric analysis (TGA), density measurement, and so on. It was found that the ceramization of gamma-ray cured PVS starts above 500 K, and drastic organic-inorganic conversion occurs in the temperature range of 700-1100 K. According to the changes of mass and density, it was found that the volume shrinkage of PVS during the curing and pyrolysis processes is 80%. The SiC obtained by pyrolysis at 1573 K in argon gas atmosphere showed the density of 2500 kg/m(3) and microvickers hardness of 31.6 GPa.