Abstract: A safety device for an open-type combustor such as a room-type oil stove which is capable of quickly extinguishing the flame of the combustor upon the occurrence of oxygen starvation but which does not operate unnecessarily during ordinary shut-off operations. A thermally deformable element is mounted in the vicinity of a wick guide cylinder or the like for detecting changes in temperature in case of abnormal combustion. An interlock body provided through an operating lever operates an automatic fire-extinguishing unit in response to the thermally deformable element. An engagement/locking portion is provided in the vicinity of the thermally deformable element for engaging and locking the interlock body.