To facilitate food handling while preventing a residue of a reaction between quicklime and water from touching food even if no special attention is paid, by eliminating the way of handling food that may spoil the food by such contact because a residue of a reaction between quicklime and water may contact food in a conventional food heating unit.

The top side of an inner container 1 which stores a water sack 4 with a breaking string 2 and quicklime 5 is closed by a metal thin film and an air permeable paper 7 between which a string 2 intervenes, the inner container 1 is stored in a lower container 8 with a water-absorbing cardboard 9, the string 2 is drawn out from the lower container 8, food is stored in a steaming container 10 provided with a vent 10a in the circumferential face and the bottom. And then a female ring 14b provided in the underside of the upper container 14 is fitted into the collar 8a at the upper end of the lower container 8 and is made to the surround the steaming container 10 placed on the air permeable paper 7 is surrounded, a suspended wall 14a is provided inside the upper container 14, and a collar 10b is formed on the top side of the steaming container 10 in a position overlapping it, and an engagement recess 14d and an engagement projection 15a are provided in the upper container 14 and a lid 15 covering the open top thereof.