PURPOSE: To enable the control of matrix hardness and to obtain an appropriate diamond tool according to purpose by using, as a metal matrix in which diamond is to be embedded, cobalt where boron in a specific amount is uniformly distributed.

CONSTITUTION: In the method for manufacture of a diamond tool by subjecting a mixture of diamond powder and matrix metal powder to pressing and to sintering, a cobalt powder previously alloyed with boron and having 1-5 wt.% boron content is used as the matrix metal powder. At this time, a diamond tool is manufactured by forming the powder mixture into a structure useful for one or more purposes among cutting, sawing, drilling, and polishing of stone, rock, glass, metal, ceramics, and other mineral materials. This matrix is uniform and can control Brinell hardness to about 200 to 650 HB30 by regulation of boron content and can maintain its hardness constant even after use.