PROBLEM TO BE SOLVED: To provide a guide wire holder capable of simultaneously flushing a catheter and a guide wire and adjusting a fixing position to the guide wire.SOLUTION: A guide wire holder 10 includes: a body 20 that is formed with a guide wire insertion path 25 and provided with a syringe connection part 33 at a proximal end a cap 40 provided with a catheter connection part 45 at a distal end and a screw part 41 at a proximal end, the screw part being inserted into and threadedly engaged with a distal end inner periphery a chuck 60 that is provided separately from or integrally with the proximal end side with respect to the screw part 41 of the cap 40 and, when the cap 40 is threadedly engaged with the distal end side of the body 20, is tightened to clamp the guide wire and seal means that seals a clearance between the body 20 and the cap 40.
