PURPOSE: To simplify a procedure of setting heating conditions in the case heating compartments are heated under the same conditions, by providing a heating condition application device by which heating conditions set by operating a setting device are applied to controls of both heating compartments by a controller.

CONSTITUTION: In the case heating compartments 1 and 2 are heated under the same conditions, the heating conditions are set for the first heating compartment 1 and a heating condition application key 16 is pressed. Thereby, the heating conditions are stored in a controller 6 and simultaneously the operation of the heating condition application key 16 is also stored and distinguished. Then, a signal R is issued to change a relay switch 9 over to the ON contact side, a signal B is output to start an air fan 5, ventilation is started and control signals C1 are output according to the heating conditions for the first heating compartment 1. In this case, the signals C1 are given both first and second magnetron drivers 11 and 12 by switching the relay switch 9. Therefore, the heating compartments 1 and 2 are simultaneously heated under the same conditions, following outputs of the control signals C1.