Provided is a fast-acting foaming solid preparation for washing oral cavity whereby tongue coating mainly causative of physiological bad breath can be effectively removed. By treating the upper face of the tongue with a solid preparation which contains an insoluble plant fiber and a foaming component, tongue coating mainly causative of physiological bad breath is mechanically separated from the tongue due to fine projections formed on the surface of the preparation. The separated tongue coating fragments are effectively collected and removed by the foaming effect of the foaming component. Thus, a foaming solid preparation for washing oral cavity, which has a remarkable effect of removing tongue coating and a fast-acting effect of preventing bad breath that can be sustainedly exerted over a long period of time, can be obtained.
