The device for mounting a cooking apparatus of the present invention under a horizontal plate such as a bottom plate of wall cabinet comprises an upper flat metallic plate fixedly mounted on the upper surface of the horizontal plate and lower metallic fitting member fixedly mounted on the lower surface of the horizontal plate; sliding metallic member engaged on the lower metallic fitting member in a laterally slidable manner; and a stopper for fixing a relative position between the lower metallic fitting member and the sliding metallic member. The cooking apparatus is supported by hanging the engaging portions formed in the side end portions of the lower metallic fitting member and the sliding metallic member on handles provided on both the left and right side surfaces of the cooking apparatus. Accordingly, the cooking apparatus can be easily mounted on a bottom plate of wall cabinets and the like without any extra member to be mounted on the cooking apparatus, so that a cooking apparatus of the type originally used by being placed on a cooking counter and the like can be easily mounted under the bottom plate of a wall cabinet and the like.