Provided are a method for manufacturing a threaded bottle can and a threaded bottle can with which a thread forming process can be performed without scratching an inside surface coating and which improves resealing operability. The opening part of a cylindrical body with a bottom is reduced in diameter and a shoulder part is formed, and above this shoulder part, a cylindrical part (11) having an outside diameter intermediate between the high parts and low parts of the threads and a tapered part (14) in which the diameter is progressively reduced toward the opening end part from the upper end of the cylindrical part (11) are formed. A thread forming process is carried out from the tapered part through the cylindrical part such that a thread starting part is formed at an intermediate position on the tapered part (14).