Surgical instrument, in particular an instrument for neurosurgery, comprising: - a shaft wherein a joint section is formed on the shaft, - a support piece with a passage extending from a distal to a proximal end for receiving at least a proximal portion of the shaft, - a proximal handling portion at a proximal end of the shaft, - a distal effector at a distal end of the shaft, and - an interface at which the instrument can be disassembled into a distal and a proximal part, wherein the instrument can be disassembled at the interface into a distal shaft assembly and a proximal handle, wherein the effector is controlled by an actuating mechanism which includes a push piece, and wherein the effector includes a first jaw part and a second jaw part which are pivotable relative to each other, wherein the push piece is movable distally to move the first jaw part and the second jaw part towards each other and to close them, characterized in that the interface comprises on the side of the shaft assembly a pressure piece and on the side of the handle a slider which can be plugged onto the pressure piece which can be coupled with the slider for force transmission into the pressure piece, the pressure piece is provided at the proximal end of the push piece, wherein the push piece is pre-tensioned proximally by a spring extending between the pressure piece and a distal stop on the support piece to urge the push piece towards the proximal end, and the slider is arranged to transmit a sliding movement to the pressure piece to move the push piece towards the distal end of the instrument. - a shaft wherein a joint section is formed on the shaft, - a support piece with a passage extending from a distal to a proximal end for receiving at least a proximal portion of the shaft, - a proximal handling portion at a proximal end of the shaft, - a distal effector at a distal end of the shaft, and - an interface at which the instrument can be disassembled into a distal and a proximal part, wherein the instrument can be disassembled at the interface into a distal shaft assembly and a proximal handle, wherein the effector is controlled by an actuating mechanism which includes a push piece, and wherein the effector includes a first jaw part and a second jaw part which are pivotable relative to each other, wherein the push piece is movable distally to move the first jaw part and the second jaw part towards each other and to close them, characterized in that the interface comprises on the side of the shaft assembly a pressure piece and on the side of the handle a slider which can be plugged onto the pressure piece which can be coupled with the slider for force transmission into the pressure piece, the pressure piece is provided at the proximal end of the push piece, wherein the push piece is pre-tensioned proximally by a spring extending between the pressure piece and a distal stop on the support piece to urge the push piece towards the proximal end, and the slider is arranged to transmit a sliding movement to the pressure piece to move the push piece towards the distal end of the instrument. wherein the effector is controlled by an actuating mechanism which includes a push piece, and wherein the effector includes a first jaw part and a second jaw part which are pivotable relative to each other, wherein the push piece is movable distally to move the first jaw part and the second jaw part towards each other and to close them, characterized in that the interface comprises on the side of the shaft assembly a pressure piece and on the side of the handle a slider which can be plugged onto the pressure piece which can be coupled with the slider for force transmission into the pressure piece, the pressure piece is provided at the proximal end of the push piece, wherein the push piece is pre-tensioned proximally by a spring extending between the pressure piece and a distal stop on the support piece to urge the push piece towards the proximal end, and the slider is arranged to transmit a sliding movement to the pressure piece to move the push piece towards the distal end of the instrument.