A forceps type treatment instrument comprising: a forceps support member that includes a first arm portion and a second arm portion attached to a distal end of a sheath and facing each other; a first forceps piece and a second forceps piece which are interposed between the first arm portion and the second arm portion of the forceps support member ; and a spacer member that rotatably supports each of the first forceps piece and the second forceps piece , wherein the first forceps piece includes a first shaft hole , wherein the second forceps piece includes a second shaft hole , wherein the spacer member includes a first shaft portion rotatably inserted into the first shaft hole and a second shaft portion rotatably inserted into the second shaft hole , characterized in that the spacer member is provided with one of a first protrusion portion or a first notch portion and one of a second protrusion portion or a second notch portion , wherein an inner peripheral surface of the first shaft hole is provided with the other of the first protrusion portion or the first notch portion , wherein an inner peripheral surface of the second shaft hole is provided with the other of the second protrusion portion or the second notch portion , wherein the first notch portion is provided with a first end portion with which the first protrusion portion comes into contact when the first forceps piece is rotated in a first direction and a second end portion which is the other end facing the first end portion , and wherein the second notch portion is provided with a third end portion with which the second protrusion portion comes into contact when the second forceps piece is rotated in a second direction opposite to the first direction and a fourth end portion which is the other end facing the third end portion . a forceps support member that includes a first arm portion and a second arm portion attached to a distal end of a sheath and facing each other; a first forceps piece and a second forceps piece which are interposed between the first arm portion and the second arm portion of the forceps support member ; and a spacer member that rotatably supports each of the first forceps piece and the second forceps piece , wherein the first forceps piece includes a first shaft hole , wherein the second forceps piece includes a second shaft hole , wherein the spacer member includes a first shaft portion rotatably inserted into the first shaft hole and a second shaft portion rotatably inserted into the second shaft hole , characterized in that the spacer member is provided with one of a first protrusion portion or a first notch portion and one of a second protrusion portion or a second notch portion , wherein an inner peripheral surface of the first shaft hole is provided with the other of the first protrusion portion or the first notch portion , wherein an inner peripheral surface of the second shaft hole is provided with the other of the second protrusion portion or the second notch portion , wherein the first notch portion is provided with a first end portion with which the first protrusion portion comes into contact when the first forceps piece is rotated in a first direction and a second end portion which is the other end facing the first end portion , and wherein the second notch portion is provided with a third end portion with which the second protrusion portion comes into contact when the second forceps piece is rotated in a second direction opposite to the first direction and a fourth end portion which is the other end facing the third end portion . <EOS>