A pair of manipulators are caused to take a plurality of attitudes in a state where distal ends of the manipulators are coupled to each other, coordinates of joints between links at each attitude change are acquired on the basis of detection signals, at each attitude change, of rotary encoders provided for servomotors that drive the links of the manipulators, and a position and attitude of an installation point of a slave robot with reference to an installation point of a master robot are calculated on the basis of the joint coordinates acquired at the corresponding attitude change in a forward kinematics manner. A deviation vector for each attitude change between actual measured values of the installation point of the slave robot and the calculated values of the installation point of the slave robot is calculated, and robot constants of both manipulators are identified from the deviation vector.