A camera body includes a body-side bayonet lug, wherein a lens-side bayonet lug of a lens barrel is positioned immediately behind the body-side bayonet lug when the lens barrel is mounted to the camera body; an opposed surface formed on the rear surface of the body-side bayonet lug and positioned immediately in front of the lens-side bayonet lug; a body-side mount surface positioned in front of the opposed surface and with which the lens-side bayonet surface comes into contact; and a body-side contact portion, the front end of which contacts the rear end of the lens-side contact portion when the opposed surface faces the lens-side bayonet lug, the front end of the body-side contact portion being positioned in front of the opposed surface and behind the body-side mount surface.