A sharing system includes an authentication device arranged in an operation subject. The sharing system includes mobile terminals that obtain code information required to use the operation subject. The mobile terminals are allowed by the authentication device to operate the operation subject if authenticated through communication with the authentication device. The sharing system further includes a terminal checking unit that checks how many of the mobile terminals located near the authentication device can connect to the authentication device in a manner allowing for communication and can operate the operation subject. The sharing system further includes a connection switching unit that switches a connection mode of the mobile terminals that are connected to the authentication device in a manner allowing for communication based on a checking result of the terminal checking unit.