AUXILIARY BATTERY

An auxiliary battery is provided. An auxiliary battery, according to one embodiment of the present invention, comprises: a main body comprising a case, a circuit board built into the case, and charge and discharge ports mounted on the circuit board; and a battery unit which comprises a plate-shaped flexible battery having a predetermined area and a soft cover member covering the flexible battery, and is coupled to the main body such that the flexible battery is electrically connected to the circuit board, wherein the cover member may be formed of a flexible and waterproof material.