PROBLEM TO BE SOLVED: To provide a living organ dilator for suppressing movement of a stent attached onto a balloon and having excellent attachment performance of the stent onto the balloon.SOLUTION: The living organ dilator 1 includes: a shaft body a balloon 3 provided at a distal end part of the shaft body and a stent 10 attached onto the balloon. The shaft body includes: a lumen one end of which communicates with the inside of the balloon and a projection part 15 made of a water swelling material, provided on an outer surface of the shaft body which is inside the balloon, proximate to the distal end of the stent 10, and a little closer to the distal end side than the stent 10. The projection part made of the water swelling material is swollen and expanded by liquid poured for priming the inside of the balloon to suppress the movement of the stent in an distal end direction of the stent toward the distal end side.
