A method of producing a rice cake that becomes not hardened for a long time period, a rice cake produced by using the method, and a processed food produced by processing the rice cake are provided. The method includes: (a) immersing grains in water and removing the water therefrom; (b) grinding the grains from which water is removed, adding water thereto, and then grinding the grains to which water is added; (c) steaming the ground grains; and (d) cooling the steamed grains, adding flour thereto, and then punching the resultant product. The rice cake has a long storage time and is suitable for a long-term distribution. The rice cake preserves its soft texture for a long time period and is thus appropriate for consumers' acceptability.