A biopsy system includes an endoscope having an insertion portion provided with a channel and an active bending section disposed in part of the insertion portion, and a treatment tool. The treatment tool has a sheath capable of being inserted into the channel and a needle tube disposed inside the sheath. The sheath has a distal tube portion including a distal end of the sheath and a proximal tube portion fixed to a proximal end of the distal tube portion and less flexible than the distal tube portion. A connecting portion acting as a boundary portion between the distal tube portion and the proximal tube portion is placed in a proximal side relative to a proximal end of a bending section in a positional relationship in which the distal end of the sheath protrudes from a distal end of the channel and is optically observable by the endoscope.
