The imaging device 102, to which an extension device 103 for accommodating an external battery 202 can be detachably attached, comprises a main body 102a for accommodating an internal battery 201, a charge IC 231, an operation unit 160, and a charge microcomputer 232. The charge IC 231 charges the internal battery 201 or the external battery 202 with power input from outside. The operation unit 160 receives an input for setting a use order of the internal battery 201 and the external battery 202. The charge microcomputer 232 controls the charge IC 231 so as to charge the internal battery 201 or the external battery 202 according to the priority order.