TiB whisker reinforced Ti alloy matrix (Ti–TiB) composites have attracted attention as the aerospace materials with their high specific mechanical properties for long time. However, strengthening mechanism of Ti–TiB composites has not been revealed because of the agglomeration and incomplete precipitation of TiB whiskers in the Ti alloy matrix yet. In this study, we addressed to fabricate fully-dense TiB whisker reinforced Ti-6Al-4V alloy matrix (Ti6Al4V–TiB) composites via powder metallurgical process, which have the microstructure to discuss their tensile properties with the theories for composite materials. The Young’s modulus and ultimate tensile strength of Ti6Al4V– 10 vol% TiB composite were 130 GPa and 1193 MPa, respectively. Note that the elongation of Ti6Al4V–10 vol% TiB composite was approximately 2.8% although the elongations of Ti–TiB composite have been reported are few (; less than 1%) due to the agglomeration of TiB whiskers in Ti matrix.