A control portion shifts a state of a self-apparatus to a power saving mode if a duration of an operation event wait state has reached a preset power saving shift set time. Further, the control portion temporarily changes the power saving shift set time to a longer time if an extension condition is satisfied. The extension condition includes occurrence, with a predetermined frequency, of a situation where a target parameter value satisfies a predetermined short-term return condition. The target parameter value is a duration of the power saving mode at a time of state return or a value of a parameter which changes in accordance with the duration of the power saving mode.