A shut-off valve for the liquid channel of a surgical instrument with a plug which is rotatably mounted and includes a cone part located in the front that includes a cone surface and a handle part located in the rear that includes a handle, wherein the liquid channel passes through the cone part, the cone surface and the housing, wherein the cone part and the handle part are mounted displaceably in the direction of the cone axis and non-rotatably against each other and supported by a spring, wherein the handle part is supported to the rear on the housing and the cone part is supported to the front with a flat contact of the cone surface on the housing, characterized in that a radially outwards or inwards projecting rear pin engages in a rear circumferential groove arranged on the housing or the handle part.
