Tensile properties, Young's modulus and microstructures of β-type Ti-10Mn and Ti-14Mn that were fabricated using a metal injection molding method were investigated as a function of sintering temperature. To investigate the biocompatibility of these Ti-Mn alloys, the metallic ions released in a simulated body fluid from Ti-10Mn and Ti-14Mn that were fabricated using a cold crucible levitation melting method were evaluated by immersion tests. The tensile strengths of the sintered Ti-10Mn and Ti-14Mn achieve maximum values of 860 and 886 MPa, respectively. The Ti-14Mn sintered at 1273 K shows the lowest Young's modulus (76 GPa) among all the sintered Ti-10Mn and Ti-14Mn. The tensile strengths of the Ti-Mn alloys are equal to that of (α + β)-type Ti-6A1-4V ELI (Ti64 ELI); further, their Young's moduli were lower than that of Ti-64 ELI. The Ti ions released in a 1% lactic acid solution from the Ti-10Mn and Ti-14Mn is the same levels as that from pure Ti. The Mn ions released into 1% lactic acid solution from the Ti-10Mn and Ti-14Mn does not show a significant increase with increasing Mn content of the Ti-Mn alloys. The ratio of the amount of the Mn ion released to the amount of the (Ti + Mn) ion released in the 1% lactic acid solution corresponds to the Mn content of the Ti-Mn alloys. These results indicated that the ionrelease behaviors of the Ti-Mn alloys in the 1% lactic acid solution are the same as that of pure Ti.