Abstract: A substrate material for mounting a semiconductor device thereon, comprises a skeleton prepared by liquid-phase presintering the composition of W and/or Mo powder in which Cu and/or Ag powder is uniformly dispersed, and a Cu and/or Ag phase infiltrated into the pores of the skeleton. The total amount of Cu and/or Ag in the product is adjusted to 10-50 vol. %. The substrate material is manufactured by two steps of: presintering the Cu and/or Ag-contng. powdery composition to form a porous skeleton, and infiltrating Cu and/or Ag into the pores of the skeleton. Since the skeleton contng. Cu and/or Ag exhibits an excellent affinity to molten Cu and/or Ag, the infiltration of molten Cu and/or Ag is performed uniformly into every nook and corner of the skeleton. Consequently, the obtained product is free from pores which would deteriorate a junction plane between the substrate and a semiconductor device mounted thereon.