An endoscope system includes: an endoscope having an insertion section extending from an operation section operated by an operator into a human body, and an operation channel having a first end section having an opening at a distal end of the insertion section and a second end section passing through the insertion section and having an opening at the operation section; a tissue-collecting apparatus connected to a connecting pipeway branching from a branch section formed to the second end section in the operation channel, and capable of seizing tissue retracted into the operation channel; an aspirator for producing suction force for suctioning the tissue into the operation channel; and a suction pipeway connecting the tissue-collecting apparatus to the aspirator. The tissue-collecting apparatus has: a tissue-collecting case having a first chamber connected to the connecting pipeway, a second chamber connected to the suction pipeway, and a communication path provided to lateral walls of the first chamber and the second chamber and causing the first chamber to communicate with the second chamber; and a tissue-collecting filter detachably enclosed in the first chamber.