PURPOSE: To provide an easy detection whether food is disposed within a predetermined range on a food stand by a method wherein a small hole is pierced in the civinity of the rotation center of the food stand and a light emitter is arranged above the small hole, the light of which is emitted through the small hole and received by a light receiver arranged below the samll hole.

CONSTITUTION: A through-hole 5 of a small diameter is formed at the rotation center of the rotatable food stand 2, the light receiver 6 is arragned below the hole 5, and the light emitter 7 is arranged at the upper part of an oven case at a position opposing the light receiver 6. With this construction, if the food is not disposed within the range 4, the light from the light emitter 3 incides into the light receiver 6. This fact means that the food disposed position is out of the view angle of a photoelectric converter 3 which detects ultrared rays radiated by the food. While the light receiver 6 is receiving the light from the light emitter 3, a controller 8 turns OFF a switching mechanism to prevent the heating operation of the cooker.