PURPOSE: To manufacture the titled sintered body having improved toughness by forming the protective film of nitride, etc., onto the metal of Nb, etc., mixing and molding it with non-oxide ceramic powder such as Si3N4 and calcining said molded body at the specific temp.

CONSTITUTION: The surface on the metallic grains of one or more kinds among Nb, Ta, W, Mo, Ti and/or their alloys are nitrified, carbonated or borided to form the protective film thereof. 5W30vol.% said metallic grain body contg. the above-mentioned protective film and non-oxide ceramic powder such as Si3N4, SiC or AlN are mixed and molded. Said molded body is then calcined at 1,600W2,100°C under the ordinary pressure W applied pressure. By this method, the calcined body in which the metals contg. said protective film are dispersed to the grain boundary of the above-mentioned non-oxide ceramic calcined body, that having improved toughness without deteriorating its transverse rupture strength can be obtd.