To provide a lightweight moisture-conditioning board where problems such that a specific gravity becomes high and cracks arise from a large bending for a moisture-conditioning building material are solved.

The moisture-conditioning board is composed of a composite comprising an organic fiber porous body, slaked lime or calcium carbonate obtained by the carbonation reaction present in the pores of the organic fiber porous body, and a mixture comprising inorganic powders such as an inorganic porous powder, an inorganic waste powder, and calcium carbonate or the like as a filler.