To provide a fireproof damper for ventilation ridge which prevents flams in the event of a fire from flying outdoors through draft gaps in a house, is structured simply so as not to constitute a hindrance for making air exchange, and can work well with differing roof gradient depending upon the site of construction through easy coordination.

A fireproof damper concerned comprises a base 1 installed in such an arrangement that the plate surface furnished with draft holes 10a is st over to the draft gap W1 of a house and a lid plate 2 installed over the base 1 parallel with it apart at a distance according to the draft gap W2 where the draft holes 10a are positioned opposingly so that they can be blocked. The lid plate 2 has a projection 30 protruding from the lid plate 1 and a receptacle frame 31 to be installed on the base 1 which are held by a leg 3 coupled by a fuse 31 to blow thermally, and is supported being pulled downward by a spring 4.