To enhance the ceiling execution of a moisture absorption and desorption building material by connecting a rear face plate projected from at least one side outward on the rear face of a moisture absorption and desorption tile and provided with an attaching margin capable of nailing and screwing.

A ceiling moisture absorption and desorption building material 10 is constituted by connecting a rear face plate 12 such as an aluminum plate on the rear face of a moisture absorption and desorption tile 11, provided to be shifted on the rear face plate to the moisture absorption and desorption tile 11 in a right and left direction, and an attaching margin 13 projected from one side of the moisture absorption and desorption tile 11 outward and capable of nailing and screwing is formed. In order to fix for the ceiling substrate material of the ceiling moisture absorption and desorption building material 10, a nail is driven into the attaching margin 13 of the rear face plate 12, and the attaching margin 13 is nailed on the ceiling substrate material. Since the moisture absorption and desorption tile 11 is not adhered and can be set on a ceiling face, execution is improved, and the danger of the peeling and fall of the moisture absorption and desorption tile 11 is eliminated.