Effects of alloying elements on elastic moduli (Young's moduli) of Ti-Nb-Ta-Zr system alloys for biomedical applications were investigated. In this case, Ti-30Nb- I 10Ta-5Zr which is the simplified chemical compositional alloy of Ti-29Nb-13Ta-4.6Zr for biomedical applications has been selected as the basic alloy composition. Each alloying element content of Ti-Nb-Ta-Zr quaternary alloys was varied independently. Nb content was varied from 0 through 40 mass % by eight levels. Ta content was varied from 0 through 20 mass % by five levels. Zr content was varied from 0 through 10 mass % by five levels. Every alloy was fabricated by powder metallurgy processing, followed by forging. Ti-30Nb-10Ta-5Zr with single beta phase, which is a basic alloy composition, shows the lowest Young's modulus. omega phase precipitation in beta phase has much greater effect on increasing Young's modulus than alpha phase precipitation in Ti-Nb-Ta-Zr quaternary alloys.