A biopsy system comprising: an endoscope having an insertion portion provided with a channel and inserted into a living body, and a bending section disposed in part of the insertion portion and configured to cause part of the channel to bend; and an endoscopic treatment tool capable of being inserted into the channel, wherein the endoscope further comprises an imaging unit capable of imaging the endoscopic treatment tool and a biopsy target portion, wherein the endoscopic treatment tool has: a tubular flexible sheath capable of being inserted into the channel; a needle tube provided with a sharp end portion capable of puncturing a tissue for biopsy and disposed inside the sheath; and a manipulation portion having a needle slider connected to a proximal end of the needle tube and a manipulation body connected to a proximal end of the sheath, the manipulation portion being configured to move the needle tube inside the sheath to cause the needle tube to protrude from and retract into a distal end of the sheath by movement of the needle slider relative to the manipulation body, and wherein the sheath has: a distal tube portion disposed in a distal portion of the sheath including the distal end of the sheath; a proximal tube portion fixed to a proximal end of the distal tube portion and aligned along the same axial line as that of the distal tube portion, the proximal tube portion having flexibility lower than that of the distal tube portion; and a connecting portion, which is configured to connect the distal tube portion and the proximal tube portion, and which is positioned in a proximal side relative to a proximal end of the 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. an endoscope having an insertion portion provided with a channel and inserted into a living body, and a bending section disposed in part of the insertion portion and configured to cause part of the channel to bend; and an endoscopic treatment tool capable of being inserted into the channel, wherein the endoscope further comprises an imaging unit capable of imaging the endoscopic treatment tool and a biopsy target portion, wherein the endoscopic treatment tool has: a tubular flexible sheath capable of being inserted into the channel; a needle tube provided with a sharp end portion capable of puncturing a tissue for biopsy and disposed inside the sheath; and a manipulation portion having a needle slider connected to a proximal end of the needle tube and a manipulation body connected to a proximal end of the sheath, the manipulation portion being configured to move the needle tube inside the sheath to cause the needle tube to protrude from and retract into a distal end of the sheath by movement of the needle slider relative to the manipulation body, and a tubular flexible sheath capable of being inserted into the channel; a needle tube provided with a sharp end portion capable of puncturing a tissue for biopsy and disposed inside the sheath; and a manipulation portion having a needle slider connected to a proximal end of the needle tube and a manipulation body connected to a proximal end of the sheath, the manipulation portion being configured to move the needle tube inside the sheath to cause the needle tube to protrude from and retract into a distal end of the sheath by movement of the needle slider relative to the manipulation body, and wherein the sheath has: a distal tube portion disposed in a distal portion of the sheath including the distal end of the sheath; a proximal tube portion fixed to a proximal end of the distal tube portion and aligned along the same axial line as that of the distal tube portion, the proximal tube portion having flexibility lower than that of the distal tube portion; and a connecting portion, which is configured to connect the distal tube portion and the proximal tube portion, and which is positioned in a proximal side relative to a proximal end of the 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. a distal tube portion disposed in a distal portion of the sheath including the distal end of the sheath; a proximal tube portion fixed to a proximal end of the distal tube portion and aligned along the same axial line as that of the distal tube portion, the proximal tube portion having flexibility lower than that of the distal tube portion; and a connecting portion, which is configured to connect the distal tube portion and the proximal tube portion, and which is positioned in a proximal side relative to a proximal end of the 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.