PURPOSE: To obtain the cooker having both functions of a general gas range and a rice cooking range by a method wherein a magnet is permitted to be attracted to a ferrite only when a thermoswitch is sunk by a given scale and a gas circuit, communicating the cock of the instrument and a rice cooking valve, is opened by the magnet.

CONSTITUTION: When a lever 16 is pushed down, a magnet rod 20 and the magnet 22 are pushed up by a part 19 of the lever through a magnet rod spring 21. At this time, the thermoswitch 5 is being pushed down by a scale (a) at the recess 28 of the central part of the bottom of an exclusive pot 27 for rice cooking and the magnet 22 arrives at the ferrite 23, therefore, the magnet is attracted to the ferrite 23 and the rice cooking valve 15 is opened. When heating for cooking the rice is finished, the temprature of the ferrite 23 arrives at the Curie point of the ferrite 23, the attraction of the magnet 22 to the ferrite 23 is released by the repulsive force of the valve spring 28 for the rice cooking valve 15 and the gravity of the lever 16 and the magnet 22 is separated from the ferrite 23. At the same time, the rice cooking valve 15 is closed and the rice cooking is finished.