The present invention provides a bearing wall with a low specific gravity of as low as 1.0 or less and a wall-magnification of 2.5 or more, which is excellent in strength, fire-safety, workability, dimensional stability, freezing resistance, water resistance and earthquake resistance, and a method for manufacturing the board. The board is produced by a method that contains the steps of: preparing a slurry by dispersing a cement-based hydraulic material, a fiber reinforcing material and a lightweight aggregate into water, adding a saturated carboxylic acid to the slurry, and then forming the slurry into a sheet, dehydrating the sheet, pressing the sheet and curing the sheet. The fiber reinforcing material includes a refined fiber with a freeness of 650 ml or less and an unrefined fiber and the saturated carboxylic acid is preferably a stearic acid-based carboxylic acid or a succinic acid-based carboxylic acid.