PROBLEM TO BE SOLVED: To provide a technique of suitably sterilizing the inside of a piping such as a discharge port.SOLUTION: Provided is an ultraviolet irradiation device 10 comprising: a pipe joint 20 including a first connection part 21 capable of being connected with a first pipe 11 elongating in a first direction, a second connection part 22 capable of being connected with a second pipe 12 elongating in a second direction crossed with the first direction and a body part 24 located in a space between the first connection part 21 and the second connection part 22； and a light source 30 composed so as to irradiate ultraviolet light from the body part 24 toward the inside of the first pipe 21. The ultraviolet irradiation device 10 may include a window member 40 provided at the body part 24 and penetrating the ultraviolet light from the light source 30.SELECTED DRAWING: Figure 1【課題】吐出口などの配管内を適切に殺菌する技術を提供する。【解決手段】紫外光照射装置１０は、第１方向に延びる第１の管１１と接続可能な第１接続部２１と、第１方向と交差する第２方向に延びる第２の管１２と接続可能な第２接続部２２と、第１接続部２１と第２接続部２２の間に位置する本体部２４と、を有する管継手２０と、本体部２４から第１の管２１の内部に向けて紫外光を照射するよう構成される光源３０と、を備える。紫外光照射装置１０は、本体部２４に設けられ、光源３０からの紫外光を透過する窓部材４０を備えてもよい。【選択図】図１
