To provide a porous ceiling ensuring an evacuation time of a resident by quickly emitting smoke filled in a habitable room to the ceiling space in case of fire.

A ceiling board 1 is formed of a porous plate, a plurality of small holes 2 having at least 30 to 50% of opening ratio are perforated in the whole surface, and when the small holes 2 are looked up from below, the ceiling board has such an extent of thickness that a visual field angle is getting narrow, and the ceiling board 1 is supported by lattice-like ceiling board underlayers 5 of T-bars 4 having a thin width.