Light irradiation medical device

A light irradiation medical device comprising:

• a shaft having a first end and a second end in a longitudinal direction, the shaft having a lumen extending in the longitudinal direction;
• and
• a light guiding device disposed in the lumen of the shaft so that the light guiding device is movable in the lumen of the shaft in the longitudinal direction, wherein
• the light guiding device extends in the longitudinal direction and has a light diffusion part at a distal part of the light guiding device,
• the shaft has a first window provided in a peripheral wall of a distal part of the shaft and a second window provided at a distal end face of the shaft, and
• the shaft has a reflection surface that reflects light emitted from the light guiding device, the reflection surface being disposed distal to the first window and on an inner side of the shaft.