Provided is a guide wire with which safety can be achieved by suppressing an incorrect puncture of a puncture part for performing puncturing. The present invention is a guide wire (10) for guiding a dilator (40) to be inserted into a living body, the guide wire having an elongated shaft part (11) that is flexible, a puncture part (15) that is disposed on a distal end part of the shaft part (11) and forms a hole in a biological tissue, and a cover part (30) that is elastically deformable and covers the puncture part (15). The cover part (30) has a coarse pitch part (36) that has a helically wound wire rod (31) and that is contractable along the center axis (X) of the winding, and a distal end cover (30B) that is located on the distal end side of the coarse pitch part (36) and covers at least a portion of the puncture part (15). The puncture part (15) has a first contact part (16) and the distal end cover (30B) has a second contact part (39) that can come into contact with the first contact part (16) from the proximal end side, wherein the relative axial movements of the first contact part (16) and the second contact part (39) are restricted by a contact made by the first contact part (16) to the second contact part (39).L'invention concerne un fil de guidage permettant de réduire les erreurs de perforation dues à une partie de perforation effectuant l'opération de perforation, et lequel permet une bonne stabilité. Plus spécifiquement, ce fil de guidage (10) est destiné à guider un dilatateur (40) devant être introduit dans un corps vivant, et comporte: une partie tige (11) allongée et flexible； une partie de perforation (15) située à l'extrémité avant de la partie tige (11) et formant un trou dans un tissu vivant； et une partie enveloppe (30) recouvrant la partie de perforation (15) et déformable élastiquement. La partie enveloppe (30) possède: une partie inclinée fine (36) contractable le long d'un axe central (X) d'enroulement qui présente un fil (31) enroulé de fa
