Glutinous rice which is steamed by a conventional method is highly sticky and becomes clumpedduring the koji making process. Thus, a new method was studied. We applied the heat-blasting method to the glutinous rice treatment. A new method for making mirin koji was constructed as follows: After the heat-blasting treatment, glutinous rice was soaked and steamed. This method is very effective for making glutinous rice koji . The glutinous rice koji using this heat-blasting method shows good disentanglibility and no excessive stickness. In addition, its characteristics included the facts that mycelia of the koji mold grew over the whole surface of the rice grains, mycelia easily entered into the internal area of rice grains, and that the resulting koji is far better. Furthermore, it showed good solubility during the maturation of mirin, and increased the yield of the hydrolytic products.