The present invention relates to a battery package attached to an external substrate, which includes an electronic circuit and a power terminal electrically connected to the electronic circuit, to supply power to the electronic circuit, or to accumulate energy by collecting power. A battery package, according to an exemplary embodiment, comprises: a battery unit that has one or more secondary battery cells and leads that are connected to the secondary battery cells and exposed; a flexible encapsulation body that accommodates the battery unit therein; exposed electrodes that are exposed on the surface of the flexible encapsulation body and are electrically connected to the leads to electrically connect to the electronic circuit; and a first Velcro part mounted on the surface of the flexible encapsulation body. The first Velcro part of the battery package is coupled to a second Velcro part mounted on the external substrate to detachably fix the battery package to the external substrate, and the exposed electrodes of the battery package and the power terminal of the external substrate are connected to each other to form a power circuit for the electronic circuit.