Information terminal device, input/output control method and storing medium

1. Field of the Invention A driver stores an electricity consumption value of corresponding input/output hardware. The stored electricity consumption value is registered in an electricity consumption value table in accordance with a setting of the driver when an operating system carries out input/output function. When an application program requires to use the input/output function, the operating system judges whether or not the required input/output of data can be stably carried out with the remaining quantity of the battery measured by a battery remaining quantity measuring instrument, and it is judged that the input/output can be carried out stable, the operating system allows a corresponding driver to drive the input/output hardware. With this feature, the operation of an input/output device is prevented from being unstabilized due to shortage of battery volume without changing an operating system even when electricity consumption of the input/output device is varied due to a setting or the input/output device is exchanged or newly added.