To provide a sliding mode controlling apparatus capable of satisfying a plurality of requirements without any contradiction at the time of controlling the behavior of an elastic system such as a spring mass system.

An exhaust valve 1 is provided with a valve body 2 and an armature 34 coupled to a valve shaft 4. Then, the valve body 2 is attracted to its valve closing position by the electromagnetic force of a valve opening drive electromagnet 36 acting to the armature 34. Also, the valve body 2 is attracted to its valve closing direction by the electromagnetic force of a valve closing drive electromagnet 38 acting to the armature 34. At the time of controlling valve opening and valve closing, the displacement of the valve body 2 is detected by a displacement quantity sensor 42. Then, a sliding mode is controlled by using a switching hyperplane variably set in accordance with the detected displacement.