A process for preparing nutritious cooked rice in an aseptic package, by mixing ginseng, jujube, chestnut and black rice, which has excellent taste and smell and capability of long-term preservation at room temperature. The process includes treating ginseng, jujube and chestnut with a mixed solution of an aqueous solution of calcium and an aqueous solution of 0.1-0.3% organic acid or phosphoric acid, mixing with non-glutinous rice, glutinous rice and black rice at a fixed rate, filling a fixed amount of the mixture automatically in a heat-resisting plastic container, sterilizing the mixture 4-10 times repeatedly for 4-8 seconds at a high temperature of 130-150.degree. C. and high pressure, cooking the sterilized mixture in a measured amount of liquid for cooking, sealing and packaging the resultant cooked rice mixture aseptically so that nutritious cooked rice which is free from microorganism and capable of long term preservation (more than 6 months) can be obtained.