To obtain smooth and uniform controllability whose readiness to the change of manipulated variable is satisfactory, by turning on and off a control object so that virtual energy many converge on energy reference value based on the consumption and filling quantity of virtual energy that is set in accordance with manipulated amount.

Energy reference value, energy consumption and the ratio of filling quantity are set (S100) and the energy reference value is stored (S101). Next, an input of a clock signal is decided (S102) and compared by an energy comparison step (S103), and when the energy value at the present time is ≥the energy reference value, a switch element is closed and a control object is turned on (S104). Energy consumption is substrated from the energy value and storage value is updated (S105). On the other hand, a comparison result is smaller than the energy reference value at the step (S103), the switch element is opened (S107), energy filling quantity is added to the energy value and storage value is updated (S108).