PURPOSE: To prevent the occurrence of accident on top plate surface, by a method wherein, in case a heated cooking pan is positioned displaced in position, an alarming device is acutated by means of heat-sensitive objects imbedded.

CONSTITUTION: A hot plate 2 is mounted on the same level in a central part of top plate 1, and a plural number of heat-sensitive objects 4 are imbedded around the hot plate. A stainless outer case 5 of the heat-sensitive object 4 is exposed so that it is set in the same level with the upper surface of the top plate 1, and a bimetal 6 works on a switch which is actuated by means of a control element 9 through a pushing member 7. In case of a pan 1 is located displaced in a position from the hot plate 2, a switch 8 is closed to actuate an alarming device.