It is a task of the present application to provide a butt position detecting method for a weld joint and a butt position detecting device for a weld joint that can detect a position of a butt portion between both members with high accuracy while reducing costs, and a manufacturing a weld joint that carries out the butt position detecting method. Thus, according to one aspect of the invention, in a butt position detecting method for a weld joint, when an arrangement direction of a first member and a second member is defined as a first direction, and a direction that is perpendicular to the first direction is defined as a second direction, the first member has a corner portion and a chamfer portion, and a two-dimensional displacement sensor is arranged at a position offset from the butt portion toward the first member side in the first direction, and such that an angle ¸s at which the second direction and an optical axis direction of irradiation light of the two-dimensional displacement sensor intersect with each other and an angle ¸a at which the second direction and a formation direction of the chamfer portion of the first member intersect with each other satisfy a condition expression: 0°