PURPOSE: To manufacture the title composite body with diamond particles bound in an independently separated state by binding many diamond particles each covered with a Ni-P alloy thin film by use of an ultra hard carbide alloy.

CONSTITUTION: A mixt. of many diamond particles each covered with a Ni-P alloy thin film and many particles of ultra hard carbide such as tungsten carbide with many fine particles of Co, Ni or Fe as an alloying element deposited in layers is prepared as starting material. This material is treated at a temp. and a press. for sintering satisfying stable temp. and press. conditions for diamond, thereby filling up a binding region which is an ultra hard carbide alloy sintered structure formed by sintering the carbide particles among the diamond particles. While maintaining the press. at this state, the treated material is cooled from the outside to solidify the metal portions, thus manufacturing a diamond-ultra hard carbide alloy composite consolidated body.