A surgical system is provided with: a first medical instrument that is disposed inside a body cavity and that has an observation unit and a marking unit that is capable of being positioned with respect to the body cavity； a second medical instrument that is disposed outside the body cavity and that has a treatment section and a driving unit for driving the treatment section； a distance measuring unit that measures the distance between the marking unit and the treatment section； and a control unit that controls the driving unit on the basis of the distance measured by the distance measuring unit.
