The disclosed technology is directed to a surgical instrument comprises a sheath having respective opposed proximal and distal ends. A pair of grasps is disposed on the distal-end portion of the sheath gripping a treatment target therebetween. A drive shaft is coupled to at least one of the pair of grasps to open or to close the pair of grasps by being moved along the longitudinal axis with respect to the sheath. Electric elements are used to apply treatment energy to the treatment target. A first operating device supplies the electric energy to the electric elements in a first supply state. A first member produces a force to open or close the pair of grasps and applies the force to the drive shaft. A second member is disposed in line with the first member and applies a force to the drive shaft in response to the operation input.
