PURPOSE: To eliminate a lateral deviation of a gridiron in the case of cooking to roast by using the gridiron and to obviate a fear of losing the gridiron.

CONSTITUTION: A cooker case 11 is so constructed that a peripheral edge 11a of a top plate 18 is relatively higher than an upper surface of the plate 18, and a gridiron disposing part 19 having a small step is formed in a circular shape on an upper inside of the part 11a. When a gridiron 20 is disposed on the part 19, an uppermost part of the gridiron 20 (an upper surface of a wire material 20b) is higher than the uppermost part 11b of the peripheral edge of the plate 18 of the case 11.