A portable electronic appliance, such as a portable computer, includes a battery receiving room, disposed within the main body, and a switching device for allowing a user to check the battery capacity outside of the appliance without removing the battery from the appliance. The battery, detachably installed in the room, has both a battery checking switch and a capacity display on one surface thereof. The battery checking switch is selectively operated outside of the appliance, while the capacity display is selectively operated in conjunction with the battery checking switch so as to display the battery capacity thereon. A window is formed on the battery receiving room at a position corresponding to the capacity display, thus allowing a user to check the battery capacity outside of the appliance by viewing the capacity display through the window.