To improve water resistance while keeping the characteristics originally belonging to aluminum nitride such as thermal conductivity, electric insulation by allowing aluminum nitride to include a specific amount of silicon carbide.

A mixture is obtained by mixing aluminum nitride having ≤10 μm, preferably 1-5 μm average particle diameter, 0.1-25 wt.% silicon carbide having ≤5 μm average particle diameter, optionally 0.5-7 pts.wt., preferably 1-5 pts.wt. reaction promoter or sintering auxiliary such as a rare metal compound and alkaline earth metal compound based on 100 pts.wt. total of the aluminum nitride and the silicon carbide. The objective water resistant aluminum nitride is obtained by optionally granulating or compacting the mixture, thereafter firing the mixture in an atmosphere containing nitrogen at 1,500-2,200°C, preferably 1,700-2,000°C for ≥10 min. At least a part of the silicon carbide forms a solid solution with the obtained water resistant aluminum nitride, and the proportion of the solid solution in the included silicon carbide is 20-100 wt.%, preferably 50-100 wt.%.