PURPOSE: To provide a method capable of manufacturing a high-purity alumina substrate which excels in dimensional accuracy and is small in warp and surface roughness.

CONSTITUTION: Polyvinyl alcohol is dissolved into water and then added to the mixture of alumina powder, water and a dispersing agent and after that, atomized and dried to obtain granular powder. An additive agent is added, as required, to the granular powder, water and water-soluble organic binder to be kneaded and then molded by extruding. After that, the gained moldings are baked.