A robot interference prevention control device reads in advance a teaching program of each robot, calculates a scheduled stop position for each robot when issuing a stop command after n number of interpolation periods from the current interpolation period, and checks whether or not interference would occur at the scheduled stop position of each robot. When the robot interference prevention control device judges that a robot will interfere with another robot, it outputs a stop command at the current interpolation period. Due to this, a stop command is output before n number of interpolation periods from the interpolation period where interference would occur and thereby the occurrence of interference can be prevented.