To cook a sweet potato to its interior in a short time and to provide a customer with a baked sweet potato without waiting time.

A perforated tray 13 disposed in a cooking chamber 12 disposed in a device body 11, and the sweet potatoes are placed on the tray 13 and cooked by a far-infrared heater 14. A heat keeping chamber 15 made of stainless steel is provided adjoining the device body 11, and a face 15a adjoining the device body 11 of the heat keeping chamber 15 is provided with heat radiating holes 15b, 15c, 15d to keep warm the sweet potatoes heated using hot air generated from the cooking chamber 12.