Provided is a battery share system in which a necessary change in the scale of a battery exchange device can be made with ease and at low cost even after the start of operating a service, and the battery exchange device can be made simple without any features for rainwater resistance. A plurality of battery charging modules for holding a battery pack are attached to a support post to form a battery exchange device. A battery charging module is detachably attached to the support post, and includes a tray for guiding the battery pack to a predetermined mounting position and holding the battery pack at the mounting position. The tray includes a wireless power transmitter with a transmitter coil for contactless transmission of charging power to the battery pack, and a wireless communication device for contactless communications of battery management information with the battery pack.