Both commercially pure titanium and Ti-6Al-4V alloy have been widely used as biomaterials because of their excellent biocompatibility, corrosion resistance and mechanical properties. However, in recent years, vanadium has been found to cause cytotoxic effects and adverse tissue reactions, while aluminium has been associated with potential neurological disorders. A newly designed ${alpha}+{eta}$ type Ti alloy, Ti-10Ta-10Nb alloy showed superior properties to CP Ti and Ti-6Al-4V alloy in the point of biomaterial, and elucidated the future uses as a biomaterial. Microstructural changes of Ti-10Ta-10Nb alloy after hot-rolling, warm-rolling, solution and aging treatment were investigated. According to TEM results, the microstructures after solution treatment were composed of mostly ${alpha}$ phase with a trace of ${eta}$ phase due to adding ${eta}$-phase stabilizer tantalum and niobium. The microstructures after warm-rolling is coarse and elongated ${alpha}$ phase and hot rolling resulted in very fine ${alpha}$ widmanst$ddot{a}$tten. The highest value of hardness was obtained by aging treatment at $400^{circ}C$ for 20hr in which microstructure consisted of very fine ${alpha}$ phase in ${eta}$ matrix.