To remove excessive water before heat curing by overlapping a filter cloth passing water through the back of a fiber-reinforced plastic template with recessed and/or projected patterns as water paths but not passing a solid cement raw material on its back, placing a cement raw material on the template surface, overlapping structures thus formed in a plurality of stages and clamping them.

A template 1 with its surface side facing upward is placed on a conveyor 2, and a fiber-reinforced cement raw material 3 is dropped on the template 1 and a filter cloth 4 passing water by not passing a solid cement raw material is overlapped on a mat-shaped raw material 3 smoothed into the given thickness to form one set with the template 1. The structure is so overlapped as to set the back of the template 1 on a lower layer of one upper sheet on the plane plate 4 on the upper layer of one lower sheet in several stages to several tens stages on a truck 5. Water squeezed out by clamping a press 6 by the given pressure is discharged out of a clearance between the template 1 and the filter cloth 4 to the outside and introduced into a heat insulation curing chamber 7 to manufacture a cement board 9. Excessive water contained in the cement raw material 3 can be discharged outside a system before heat curing by the arrangement.