To provide a fire damper for a paper slip air shooter duct, which securely allows cut paper slips to pass through along a carrier conduit in ordinary circumstances, and shuts its duct in case of fire or the like.

The fire damper 1 includes a paper slip carrier conduit part 20 comprising a reducer-shaped space 22 whose both tube ends are set to be a diameter of a paper slip carrier conduit 2, on whose central upper part a cuboid-shaped chamber 10 is mounted, and whose cross section changes to a position of the chamber 10, and a variable cross section space 21 under the chamber 10. A blade part 11 to form a bottom surface of the chamber 10 and rotatably pivoted by a rotation axis 13 pivoted on an outer surface of the variable cross section space 21 is provided therein. The blade part 11 functions as a partition plate to almost cover the bottom surface of the chamber 10 in ordinary circumstances. When the temperature fuse 31 of the paper slip carrier conduit part 20 detects fire, the blade part 11 rotates around the rotation axis 13 and stands up by the tractive force of a tractive spring 33, and closes the chamber 10 and the paper slip carrier conduit part 20 in the variable cross section space 21.