An intermediate adapter includes a first terminal operable to be electrically connected to a lens detecting terminal provided on the camera body when the intermediate adapter is attached to the camera body, a second terminal operable to be electrically connected to a terminal provided on the interchangeable lens for providing a ground potential when the interchangeable lens is attached to the intermediate adapter, and a first switch interposed between the first terminal and the second terminal. The first switch is operable to electrically connect the first terminal and the second terminal when the first switch is on, and disconnect the electrical connection between the first terminal and the second terminal when the first switch is off. While the intermediate adapter is being attached to the interchangeable lens, the first switch is off to disconnect the electrical connection between the first terminal and the second terminal.