A treatment tool of which a treatment unit operates with a driving force generated from a driving source, the treatment tool comprising: a driving force transmission member that is connected to the driving source; a connecting portion that is formed in the treatment unit, that is connected to the driving force transmission member, that is supplied with the driving force from the driving source via the driving force transmission member, and that converts the driving force into movement of the treatment unit; and a moving amount detection member that is moved by the connecting portion, wherein the connecting portion includes a connecting member to which the moving amount detection member is fixed; wherein the connecting member includes a turning portion that turns about a predetermined support point, wherein the driving force transmission member is fixed to a position on the connecting member which is separated from the predetermined support point by a first distance, wherein the moving amount detection member is fixed to a position on the connecting member which is separated from the predetermined support point by a second distance greater than the first distance, wherein the driving force transmission member and the moving amount detection member are linear members, wherein the turning portion comprises: a first pulley of which the rotation center is the predetermined support point and in which the driving force transmission member is wound on an outer periphery thereof; characterized in that the turning portion further comprises a second pulley of which the rotation center is coaxial with the rotation center of the first pulley, that has a diameter larger than that of the first pulley, and in which the moving amount detection member is wound on an outer periphery thereof; and wherein the moving amount detection member is fixed to the second pulley. a driving force transmission member that is connected to the driving source; a connecting portion that is formed in the treatment unit, that is connected to the driving force transmission member, that is supplied with the driving force from the driving source via the driving force transmission member, and that converts the driving force into movement of the treatment unit; and a moving amount detection member that is moved by the connecting portion, wherein the connecting portion includes a connecting member to which the moving amount detection member is fixed; wherein the connecting member includes a turning portion that turns about a predetermined support point, wherein the driving force transmission member is fixed to a position on the connecting member which is separated from the predetermined support point by a first distance, wherein the moving amount detection member is fixed to a position on the connecting member which is separated from the predetermined support point by a second distance greater than the first distance, wherein the driving force transmission member and the moving amount detection member are linear members, a first pulley of which the rotation center is the predetermined support point and in which the driving force transmission member is wound on an outer periphery thereof; a second pulley of which the rotation center is coaxial with the rotation center of the first pulley, that has a diameter larger than that of the first pulley, and in which the moving amount detection member is wound on an outer periphery thereof; and wherein the moving amount detection member is fixed to the second pulley.