[Problem] In order to provide a stent delivery device capable of smoothly performing a procedure when a device is inserted into a living body. [Means for Resolution] A stent delivery device 100 includes: a shaft 110 internally provided with lumens 113 and 114； a balloon 120 inflated and deflated around an axial direction of the shaft； a cover 130 configured to advance and retreat in the axial direction of the shaft between a covering position where the cover covers the deflated balloon and a retreated position where the cover is separated from the balloon； and a drive unit 150 configured to apply a driving force for advancing and retreating the cover. The balloon and the drive unit are operated by a working fluid injected or discharged through the lumen of the shaft, and the inflation and deflation of the balloon and the advancing and retreating of the cover are performed in conjunction with each other.
