The invention has for its object to provide a medical master/slave system that is improved in terms of operability when the slave apparatus is folded back, and a method of controlling the medical master/slave system comprising a bendable master apparatus operated by an operator and a slave apparatus inserted through the body. The control method includes an ordinary actuation mode (Step S101) in which, based on a bending state of the master apparatus, the slave apparatus is actuated in such a way as to become similar in operation to the master apparatus, a reversal actuation mode (Step S105) in which, based on a bending state of the master apparatus, the slave apparatus is actuated in such a way as to be reversed relative to the operation of the master apparatus, and a transition mode (Step S103, S104, S107, S108) for transition between the ordinary actuation mode and the reversal actuation mode.
