A treatment instrument for an endoscope used in combination with an endoscope having a raising base at a distal end section of a channel, the treatment instrument for the endoscope includes a sheath section having flexibility； a treatment section installed closer to a distal end side than the sheath section； and a manipulation unit installed at a proximal end of the sheath section and configured to manipulate the treatment section, wherein the sheath section has a sheath main body； a sandwiched portion formed at a distal end side of the sheath main body and sandwiched between the raising base and an inner circumferential surface of the channel； and a torque transmission member configured to transmit a rotational torque input at the proximal end side by a user and turn the sheath main body about the axis.
