PURPOSE: To inexpensively obtain the composite having a high density and high strength by preparing a tough and soft ceramic sheet from a granular ceramic substance by a specific method, then laminating this sheet on a refractory inorg. fiber sheet to multiple layers and treating the laminates.

CONSTITUTION: The slurry of the ceramic substance obtd. by mixing the granular ceramic substance (e.g.: glass powder of 10 μ in average grain size), a binder substance (e.g.: acrylic polymer), a dispersant, a thickener, deionized water, alcohol and concd. aq. NH4OH is cast onto a plastic film through an orifice of a casting basin and thereafter, the casting is dried and removed from the film to obtain the ceramic sheet. The sheets of the refractory inorg. fibers 11, 11a (e.g.: SiC fibers of 140 μ in diameter) arrayed to the open array of a single layer bonded to each other by the binder (e.g.: acrylic system) are laminated in the multiple layers so as to be alternately inserted between the ceramic sheets 20, by which a multilayered preform 30 is formed. This preform is then heated in air to remove the org. components and is further heated under pressurization so as to be completely solidified, by which the single composite substantially free from voids is obtd.