To enhance product strength by improving the texture of a green sheet in the production of a fiber reinforced cement panel.

When a cement slurry is prepared by adding reinforcing fibers and water to cement, fibrillated reinforcing fibers are again bundled to become a lumpy state according to circumstances. The cement slurry with a solid concentration of 25-60 wt.% compounded with the reinforcing fibers is applied to an attritor before papermaking processing to be subjected to dispersing treatment.