To provide a rice cooker wherein the external surface of a steam port is covered with a flexible sheet-shaped valve body, a heat loss by evaporation heat is reduced by suppressing the evaporation of required moisture by closing a steam passage after the completion of rice cooking, and at the same time, drying is prevented from occurring, and by which the taste of cooked rice does not deteriorate even after warming for long hours by solving the problem that a conventional rice cooker keeps the inside and the outside open through the steam port, and cooked rice is easy to dry, and the taste deteriorates by the warming.

By this warming dry preventive method and the sheet-like valve body, the external surface 17a of the steam port is covered with the flexible sheet-shaped valve body 19, and the valve body is detachably held so that the valve body may not drop by the opening/closure of a lid. The valve body which is constituted of a flexible material having a hardness of 20 to 60° goes along and closely joins to the steam jetting port which has a curved surface, and thus a steam transpiration passage for the steam is constituted to be sealed.