Disclosed are a method of preparing rice flour having good rheological and sensory characteristics, rice flour prepared by the method, and instant rice soup including the rice flour. Specifically, there are provided a method of preparing rice flour, which has better Theological characteristics, higher material stability through killing of microorganisms during its processing, and much better taste by removal of characteristic odor of rice flour, compared to conventional rice flours or rice flours prepared by other processing methods, and also instant rice soup using the rice flour thus prepared. The rice flour of this invention may be cooked within a short time of 1 min or less through only the addition of warm water (70.about.80.degree. C.), and has no unpleasant taste and no characteristic odor occurring from conventional rice flour, thus exhibiting good sensory characteristics for instant foods. As well, since such rice flour has good texture, it may be applied to various foods requiring particular Theological characteristics.