An endoscope system includes: an endoscope having an insertion section (7) extending from an operation section (6) operated by an operator into a human body, and an operation channel (9) having a first end section (9A) 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 (23) connected to a connecting pipeway (18) 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 (4) for producing suction force for suctioning the tissue into the operation channel and a suction pipeway (10) connecting the tissue-collecting apparatus to the aspirator. The tissue-collecting apparatus has: a tissue-collecting case (24) having a first chamber (29) connected to the connecting pipeway, a second chamber (30) connected to the suction pipeway, and a communication path (31) 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 (25) detachably enclosed in the first chamber
