PURPOSE: To realize higher strength by fully giving full play to the reinforcing effect of inorganic reinforcing fiber and obtain product having no defect such as voids or the like by a method wherein inorganic hardening composition consisting of inorganic hydraulic substance, aggregate, inorganic reinforcing fiber and the like is extrusion-molded and then hardened by curing so as to obtain inorganic hardened body.

CONSTITUTION: Material M, which is prepared by kneading inorganic hydraulic substance, aggregate, thickening agent and water with a mixer and an extrusion kneader, is charged in a vacuum extrusion molder 1 and simultaneously continuous inorganic fiber G is charged in the molder 1 by means of rubber rolls 5 so as to obtain formed body F through kneading. The rotational frequencies of the pug screw 2 and of the auger screw 3 of the extruder 1 are preferably set to be 70-150% of the rotational frequencies, by which the length of inorganic reinforcing fiber in the formed body F of about 10mm is obtained.