To easily produce silicon nitride-base ceramics excellent also in workability while having excellent mechanical characteristics.

The silicon nitride-base ceramics contains a titanium compd. chiefly in the grain boundaries and has ≤100 nm average grain diameter. The Vickers hardness of the ceramics is ≥1,200 at room temp. and lowers to ≤300 at >1,000°C. The ceramics is produced as follows; silicon nitride powder and titanium powder are mixed and communicated to ≤50 nm average particle diameter by a mechanical alloying method and the resultant composite powder is heated until ≤100 nm average grain diameter is attained and the titanium compd. is distributed chiefly in the grain boundaries.