PURPOSE: To produce a sintered compact for a tool having excellent toughness, strength, wear resistance or the like by mixing the carbides or the like of transition metals, iron-group metals and fine-grained diamond in specified ratios and executing sintering at a specified temp. under a specified pressure.

CONSTITUTION: By volume, 20 to 85% carbides, nitrides or sulfides of any transition metal of the 4a, 5a and 6a group in a periodic table or their mixture or solid solution (such as WC), 2 to 30% iron-group metals (such as Co) and 10 to 50% fine-grained diamond having 10 to 40μm grain size are mixed by a ball mill or the like. As it is or after being subjected to die extrusion, this mixture is subjected to solid phase sintering at 950 to 1150°C under 1 to 30kb by a hot hydrostatic pressing device to produce a sintered compact in which fine carbon is precipitated in the iron group metals or on the surface thereof. In this way, the sintered compact for a tool excellent in workability, hardness or the like can be produced at a remarkably reduced producing cost.