To provide a method for producing a fiber reinforced cement board, by which a high strength of a final product is maintained so that the strength of the plate material after autoclave aging may not be affected, even if the strength at the first aging time is improved.

A fiber reinforced cement board obtained by blending a fumed silica with a slurry comprising a pulp fiber, an organic synthetic fiber, a cement, a quartz sand and preferably a mica as a main raw material, and compacting the blend by a well known wet method is pressed under a high pressure of 9.8-19.8 MPa, and subjected to the first aging under a condition of 40-60°C temperature. The fiber reinforced cement board hardened by the first aging is subjected to a required grinding processing, and the fiber reinforced cement board after processing is subjected to an autoclave aging at 150-180°C for 8-20 hr to provide the objective fiber reinforced cement board in the method for producing the fiber reinforced cement board.