The invention discloses an accessory. An interchangeable lens is removably attached to a camera body including a body-side mount, body-side terminal group disposed above an upper side of an image sensor and a first to fourth body-side claws. The second body-side claw extends in circumferential direction with a center angle and is located outside the body-side terminal group. The interchangeable lens includes the lens-side mount, lens-side terminal group, a first to fourth lens-side claws engaged with the first to fourth body-side claws in proper attachment of the interchangeable lens. The fourbody-side claws are respectively disposed in four regions divided by a first and second body-side lines in relation to the arc-shaped body-side terminal group. The interchangeable lens is inserted tothe camera body and rotated by a first angle for attaching and the terminals of the camera body and the interchangeable lens are connected each other. The center angle of the second body-side claw issmaller than the first angle.