PROBLEM TO BE SOLVED: To facilitate insertion of an endoscope into an indwelling catheter.SOLUTION: An endoscope system 1 includes: an insertion portion 11 in which an imaging optical system and an illumination optical system are covered with a protection tube an operational part 12 connected to a base end of the insertion portion a solution sending means 20 and a joint 30. The joint includes: a first connector part 31 which is connected to a proximal end 103 of an indwelling catheter 100 indwelled in a human body a second connector part 32 connected to an output end of the solution sending means an insertion port 33 where the insertion portion is inserted and a path 34 which communicates with the first connector part and communicates with the second connector part at one side and the insertion port at the another side via a confluence part. The insertion portion entering the path from the insertion port passes through the confluence part and the first connector part to be able to enter the indwelling catheter connected to the first connector part, and a liquid sent from the solution sending means connected to the second connector part passes through the confluence part and the first connector part to be able to flow in the indwelling catheter connected to the first connector part.
