To solve the problem that oil tends to stick to a household oil pot which contains the oil at all times and the oil stains of the oil pot is hard to remove.

An open type inner case is put into the oil pot in contact with the inner side and the upper peripheral edge of the oil pot so as to be easily exchanged and flexibly cope with the oil pot of a size in the range of a certain degree. Thus, the stains by the oil and the droplets of the oil are easily prevented.