An electronic device is provided including: a display for displaying a UI element; a processor for processing an application; a Printed Board Assembly (PBA) having the processor mounted thereon, and arranged to be substantially parallel to the display; a main battery which supplies power to the electronic device, and is rechargeable and detachable; an auxiliary battery for supplying power to the electronic device; a first frame which houses the main battery, fixes the PBA, and is arranged to be substantially parallel to the display; a second frame for fixing the display and the first frame; and a cover coupled to the second frame, wherein the first frame includes a hole for housing the auxiliary battery, and the electronic device can receive power supplied from the auxiliary battery when power supply from the main battery is terminated.