An apparatus body of an image pickup apparatus that ensures reliability of an electric connection between a lens adapter and the apparatus body with a simple configuration even when a spacer is inserted between the lens adapter that has an electrical communication unit and the apparatus body. A lens adapter to which an interchangeable lens is detachably attached is detachably attached to a fixing unit. An electrical connecting portion is formed as a comb-shaped terminal that is electrically connected with a terminal of the electrical communication unit provided in the lens adapter. A contact portion of the comb-shaped terminal contacting with the terminal of the electrical communication unit is slidable with respect to the terminal of the electrical communication unit.