Recently developed β-Ti alloy Gum Metal is one of attractive materials for biomedical applications due to its excellent combination of low Young's modulus and high strength. Gum Metal also exhibits other unique properties such as non-linear elasticity, plastic deformation without work-hardening. These multifunctional properties in Gum Metal are quite intriguing characteristics not only for practical applications but also for fundamental studies. However the mechanism is not fully understood yet. In this research, in order to obtain new information for special plastic deformation behavior of Gum Metal, the deformation texture and microstructure of Ti-(19-29)Nb-2Zr-0.7Ta-1.2O alloys including typical composition of Gum Metal were investigated by XRD measurement and TEM observation. The major deformation texture of Ti-(21-29)Nb-2Zr-0.7Ta-1.2O alloys was {001}<110> type. However, the maximum orientation density I_max in orientation distribution functions (ODFs) strongly depends on Nb content and the maximum value was obtained at Ti-23Nb-2Zr-0.7Ta-1.2O, indicating that the strongest deformation texture was formed in Gum Metal composition. TEM observation implied that the strong deformation texture formation in Gum Metal is due to its unique deformation mechanism.