To keep cooked a material submerged in the cooked liquid even when the amount of the liquid is not enough and easily take out the cooked material from the inner pot by forming the inner pot in a way that the outer circumference of the bottom is shorter than that of the top opening.

A lower side part 62a is integrally installed extending from the upper edge part of a connecting part to the bottom 60 substantially along the vertical direction. An upward stepped part 62b is spread from the upper edge part of the lower side part 62a obliquely upward to the outside of an inner pan 1 like a ring. The upper side part 62c is integrally installed extending from the upper edge part of the upward stepped part 62b parallel to the lower side part 62a. That is, the inner pot 1 is formed in such a manner that the inside diameter r1 of the lower side part 62a near the bottom 60 is shorter than the inside diameter r2 of the upper side part 62c near an opening. In other words, the inner pan 1 is formed in such a manner that the inner peripheral length of the lower side part 62a near the base 60 is shorter than the inner peripheral length of the upper side part 62c near the opening.