A robot system control method includes a first step through a fifth step. Particularly in the second step, a second transformation matrix that represents the positional relation between a first slave robot and a second slave robot is generated and stored in a master robot. In the fourth step, based on a second command obtained using a first transformation matrix and the second transformation matrix, the master robot instructs the second slave robot to operate. In the fifth step, the first slave robot and the second slave robot perform a cooperative operation with the master robot. Thus, in the state where a working robot that can perform TCP matching with only part of the other robots is set to a master robot, all of the robots can perform a cooperative operation.