A process includes defining, in a memory, arm-occupied regions including robot arms and a workpiece and tool attached to a robot wrist, a virtual safety protection barrier with which the arms are not allowed to come into contact, and movable ranges of robot axes; estimating the coasting angle of each robot axis for which the axis will coast when the robot is stopped due to an emergency stop while moving to a next target position, from an actually measured amount of coasting and the like; determining a post-coasting predicted position of the robot by adding the estimated coasting angles to the next target position; checking whether or not the arm-occupied regions at the post-coasting predicted position will come into contact with the virtual safety protection barrier, or whether or not the robot axes are within the movable ranges; and performing control to stop the robot immediately upon detection of abnormality.