Titanium exhibits many attractive properties and is considered ubiquitous,having the 9th-highest Clarke number among all elements. However, titanium is classified as a rare metal because its current refinement process is non-continuous and less productive than the extraction processes used to extract iron and aluminum. Furthermore,the principal beta-stabilizing elements for titanium can he very expensive,making many titanium alloys expensive. Manganese,a beta stabilizer for titanium alloys,is also considered ubiquitous, having the llth-highest Clarke number among all elements. Once a new continuous-refinement process for titanium is developed, a very important subsequent step will be to investigate the properties of Ti-Mn alloys in order to develop new alloys composed of ubiquitous metals. This study investigated the effect of aluminum addition on phase constitution, heat treatment behavior,and tensile properties of Ti-10 mass% Mn-Al alloys through electrical resistivity • Vickers hardness and X-ray diffraction (XRD) measurements and tensile tests. In all STQed alloys, only beta phase was identified by X-ray diffraction. Resistivities at RT and LN increased monotonously with A1 content. Upon isothermal aging at 673K,isothermal omega phase precipitated and then alpha phase precipitated in 0 and 1. 5A1 alloys, whereas only alpha phase precipitated in 3. 0 and 4. 5A1 alloys. In the case of A1 addition in excess of 3mass%,isothermal omega phase precipitation was suppressed. In STQed 1. 5Al alloy for tensile test,about 950MPa and about 20% were obtained as tensile strength and elongation,respectively.