A method of manufacturing a titanium alloy with high strength and high formability, the method including preparing a titanium alloy material and equipment for manufacturing the titanium alloy, manufacturing the titanium alloy having a lamellar structure (martensite structure) by cooling the prepared titanium alloy material with water after performing heat treatment at the beta transformation temperature or more, and rolling that makes ultrafine grains by finishing forming of the titanium alloy at a plastic instability temperature or less of an initial lamellar structure by gradually decreasing the forming temperature in accordance with an increase of a strain after starting the forming at the plastic instability temperature or more of an initial lamellar structure, under a condition of a low strain in which the strain is 2.5 or less, after the manufacturing of a titanium alloy having a lamellar structure.