A surgical instrument comprising: an insertion unit; an operating unit provided on one end of the insertion unit; a treatment unit provided so as to protrude from the other end of the insertion unit in a protruding direction at a predetermined angle (θ1) to an axis of the insertion unit, the treatment unit including two gripping members (21a, 21b), each having a gripping face (23a, 25a); a first shaft member for transmitting turning force to the treatment unit in conjunction with the turning operation of a turning operation member provided on the operating unit; and a second shaft member for transmitting opening/closing force to the treatment unit in conjunction with the opening/closing operation of an opening/closing member provided on the operating unit; wherein the first shaft member and the second shaft member are positioned on approximately the same axis; wherein the treatment unit is turnable about an axis in the protruding direction according to the turning operation with the turning operation member, and the treatment unit is configured to move at least one of the two gripping members (21a, 21b), according to the opening/closing operation with the opening/closing operation member so as to be opened or closed; and wherein the first shaft member is in a pipe shape, and the second shaft member is inserted within the first shaft member, wherein the surgical instrument further comprises a wedge member with a sloping face, the wedge member being affixed to the tip portion of the treatment unit side of the second shaft member, wherein at least one of the two gripping members has a shaft member with a wedge-receiving portion, wherein in order to cause the turning force in conjunction with the turning operation of the turning operation member to be transmitted by a first bevel gear, a second bevel gear, a third bevel gear, and a fourth bevel gear turning in this order, the second bevel gear and the third bevel gear are arranged at both ends of the first shaft member, and wherein the opening/closing force in conjunction with the opening/closing operation of the opening/closing member is transmitted by the second shaft member advancing and retracting in an axis direction of the insertion unit while sliding the sloping face of the wedge member over the wedge-receiving portion. an insertion unit; an operating unit provided on one end of the insertion unit; a treatment unit provided so as to protrude from the other end of the insertion unit in a protruding direction at a predetermined angle (θ1) to an axis of the insertion unit, the treatment unit including two gripping members (21a, 21b), each having a gripping face (23a, 25a); a first shaft member for transmitting turning force to the treatment unit in conjunction with the turning operation of a turning operation member provided on the operating unit; and a second shaft member for transmitting opening/closing force to the treatment unit in conjunction with the opening/closing operation of an opening/closing member provided on the operating unit; wherein the first shaft member and the second shaft member are positioned on approximately the same axis; wherein the treatment unit is turnable about an axis in the protruding direction according to the turning operation with the turning operation member, and the treatment unit is configured to move at least one of the two gripping members (21a, 21b), according to the opening/closing operation with the opening/closing operation member so as to be opened or closed; and wherein the first shaft member is in a pipe shape, and the second shaft member is inserted within the first shaft member, wherein the surgical instrument further comprises a wedge member with a sloping face, the wedge member being affixed to the tip portion of the treatment unit side of the second shaft member, wherein at least one of the two gripping members has a shaft member with a wedge-receiving portion, wherein in order to cause the turning force in conjunction with the turning operation of the turning operation member to be transmitted by a first bevel gear, a second bevel gear, a third bevel gear, and a fourth bevel gear turning in this order, the second bevel gear and the third bevel gear are arranged at both ends of the first shaft member, and wherein the opening/closing force in conjunction with the opening/closing operation of the opening/closing member is transmitted by the second shaft member advancing and retracting in an axis direction of the insertion unit while sliding the sloping face of the wedge member over the wedge-receiving portion.