A medical elongated body including a catheter main body. The catheter main body has a tubular body and a lumen. The tubular body includes a guide wire lumen into which a guide wire is insertable. The tubular body also a distal member positioned at the distal portion of the tubular body. The distal member has a lumen that communicates with the guide wire lumen. The inner diameter of the distal member decreases between the proximal end and a distal end opening of the distal member. The medical elongated body also includes a visible marker that extends circumferentially on the outer surface of the distal member to indicate a position of the distal member in the axial direction corresponding to a predetermined inner diameter of the distal member. The visible marker is visible before the medical elongated body is inserted into a living body.
