A controller for a plant that can compensate for non-linear property and reduce oscillation of output of a controlled object even when the controlled object has high non-linear property is provided. The present invention provides a controller for a plant that uses PWM algorithm. The device calculates provisional control input for controlling output of the plant at a target value, and divides the provisional control input into a plurality of components. The controller PWM-modulates at least one of the plurality of components, and sums the PWM-modulated component and other components to produce a control input to the plant. The controller minimizes variations in input while maintaining the ability of PWM modulation to compensate for non-linear property of the plant.