To obtain uniform W-Cu type bulk solid solution composed essentially of bulky solid solution having larger volume than granular body by forming powder composed essentially of W-Cu solid solution.

At the time of manufacture, first a raw material mixture consisting of W powder and Cu powder is prepared. The mixing proportion of respective powders is determined so that the composition of the W-Cu solid solution to be finally obtained becomes W1-xCux (where 0.05≤x≤0.5 is satisfied). Then, mechanical alloying treatment is carried out to form a powder composed essentially of W-Cu solid solution. By this procedure, the alloying action of W powder and Cu powder and the uniformizing action of them can be sufficiently provided, and a W-Cu solid solution powder as a nonequilibrium substance that is impossible to obtain by the melting method can be obtained. By applying an impact pressure not lower than the yield stress of the solid solution to the resultant solid solution to compact it instantaneously, the powder can be solidified without causing phase separation and recrystallization. As the result, the W-Cu type bulk solid solution, containing bulky solid solution having diameter and volume larger than those of granular body, can easily be mass-produced.