PURPOSE: To perform the alteration of a cage ceiling by simple work by forming a suspended ceiling face of a movable plate provided with different design faces on the top and bottom faces and forming the movable plate reversibly as well as disposing a holding means for holding the movable plate in the horizontal position.

CONSTITUTION: At the time of rearranging a cage ceiling, a holding member 7 is removed so that a movable plate 6 is rotated in the direction of an arrow A to be disposed in a position indicated by a continuous line. The movable plate 6 is then moved in the direction of an arrow B through a roller 6b to be disposed in a position indicated by a chain line. The movable plate 6 is further rotated in the direction of an arrow C and held horizontally by the holding member 7, the exit 1a side of which is thrusted into a fixed body 3. The second face of the movable plate 6 can be thereby disposed downward, thus terminating rearrangement. The rearrangement in the cage can be thus performed by a simple work.