Mobile equipment with electric power supply control function

An apparatus for controlling the supply of electric power to mobile equipment has a battery checker that checks a remaining battery-level of at least one of plural batteries including main battery. The main battery is installed in a body, and the other batteries are installed in an auxiliary electric power source accessory that is detachably mounted on the body. The apparatus further has a battery-level indicator that indicates a mark so as to represent a remaining battery-level based on a plurality of grades and indicates a common mark in each grade, and a battery selector that selectively uses one of the plural batteries. When the remaining battery-level shifts over a boundary battery-level positioned between grades adjacent to each other, the battery selector selects one of the plural batteries, the remaining battery-level of which is greatest.