Even when a first moving condition is not satisfied, when it is determined that a second moving condition is satisfied and at the same time an object belongs to a second classification, an operation of a robot is controlled so as to prompt the object to move according to a first pattern or an arbitrary pattern. The “first moving condition” is a condition that the robot is capable of moving without being obstructed by the object when the robot moves according to a current target position trajectory. The “second moving condition” is a condition that the robot is capable of moving according to the current target position trajectory without being obstructed by the object when the object is displaced according to the first pattern. The “second classification” means a classification of the object which is capable of being moved by a force from the robot acting thereon.