The single-lens reflex camera body is provided with: a detector that detects which of a first lens unit or a second lens unit is attached; a rotation operator which accepts a rotating operation to adjust a diaphragm value of the lens unit attached to the camera body; and a controller which transmits the diaphragm value that is adjusted at the rotation operator to the lens unit attached to the single-lens reflex camera body, and having a configuration where an operating direction of the diaphragm ring when a rotating operation is performed at the diaphragm ring to adjust the diaphragm value is the same as an operating direction of the rotation operator when the rotating operation is performed at the rotation operator. Thereby, the diaphragm value can be set easily.