PURPOSE: To provide a method for producing a silicon nitride-based sintered compact enabling to sinter at relatively low temperatures without lowering its final sintered density and mechanical strength.

CONSTITUTION: The sintered compact can be obtained by compacting and sintering a mixture composed of (A) an appropriate amount of a sintering auxiliary and (B) the rest of silicon nitride powder containing 0.05-1wt.% of halogen element(s). Specifically, this sintered compact of 0.05-1wt.% in the content of the halogen element(s) can be obtained, for example, by incorporating (1) halogen element-contg. silicon nitride powder with (2) an appropriate amount of a sintering auxiliary to prepare stock powder which is then compacted to a desired shape followed by sintering at ≤1700°C.