A target-travel-path generating circuit calculates a target travel path along which the controlled object can travel in the future from the current controlled object position, an ideal-control-signal calculating circuit calculates a control profile Ŝ to travel along the target travel path P, and a difference calculating circuit calculates a difference δ between the ideal control magnitude Ŝ and a current control magnitude Ŝ. An operation system assistance controller controls the operation system based on the magnitude of the calculated difference δ to assist the control operation of the operator, the control-operation-state of the operator, the environment-state, and the required operation-precision. Accordingly, it is possible to provide the operator with control operation assistance that is a function of the magnitude of the difference δ from an ideal control state, the control-operation-state of the operator, the environment-state, and the required operation-precision, and thus, a control-operation assistance control can be outputted that is suitable for the conditions that characterize the state of the operator, the environment, and the controlled object.