A master-slave system (1) according to the present invention includes a slave actuator (As1 to As3) for generating a slave driving force (τs) to control a slave robot in terms of driving force, an effective driving force sensor (Fs1 to Fs3) for measuring a slave effective driving force (τsa) actually acting on a terminal output axis of the slave actuator (As1 to As3), and a slave target effective driving force calculating device (3) for calculating a slave target effective driving force (τsad) which is a target value for the slave effective driving force (τsa), on the basis of a master operating force (fm) applied to the master robot by an operator (U). The slave actuator (As1 to As3) generates the slave driving force (τs) on the basis of the slave target effective driving force (τsad) and the slave effective driving force (τsa).