Underwater-shock powder compaction on mixture of titanium and aluminum was performed under vacuum or atmospheric pressure. The mixture was held at intervals of 1 to 6 cm from bottom of powder container. Since the mixture was subject to high pressure induced by detonation of explosive, it was launched toward the bottom of container intensively. As a result, consolidated mixtures indicated hard formation of compounds, except for upper area of powder compacts. However, the powder compact consolidated under vacuum, which showed about 93% of theoretical density, indicated high density as that obtained under non-vacuume atmosphere. It was found that evacuation of air from interparticle regions affected the powder compacts. There is little fluctuation in-plane Vickers hardness in the compacts, except for upper region of the product in which Ti-Al intermetallic compound was formed. This means that homogeneous materials could be obtained generally.