To provide a board material for building which is high in strength and good in dimensional stability.

In a core layer of a board, a mixture of a wafer and/or a strand and a woody fiber bundle is used as a reinforcing material of a hydraulic inorganic material. An additional amount of the wafer and/or the strand is controlled to ≤5 wt.% in the core layer by addition of the woody fiber bundle, a dimensional stability is improved without lowering a strength, and a formability is improved. In order to obtain a sharp irregular pattern by securing a surface smoothness, a mixed raw material wherein cement based raw material of 30-60 wt.%, silicic acid-containing material of 30-60 wt.%, perlite of 0-15 wt.%, and flake and/or wood flour and/or fiber of 5-25 wt.% are mixed, is used.