The invention relates to a surgical instrument comprising a handling part and a tool part that encompasses at least one movably mounted tool which is actuated via a force-transmitting and/or actuating mechanism. Said force-transmitting and/or actuating mechanism is operated from the handling part and is provided with a fluid-operated drive unit. In order to improve said surgical instrument such that the same can be operated with as much sensitivity as possible, the movably mounted tool can be impinged upon a first acutation force in a first driven position while being impinged upon by at least one second actuation force in a least one second driven position with the aid of the drive unit.