To provide an intermediate adapter capable of performing control suitable for various lens types.

The intermediate adapter comprises: a first mount section which can attach/detach a photographic lens thereto/from having a diaphragm capable of changing an aperture diameter from the maximum aperture diameter to the minimum aperture diameter, and a diaphragm interlocking member which can move between a first position corresponding to the maximum aperture diameter and a second position corresponding to the minimum aperture diameter by interlocking with the diaphragm and which is energized at the second position by a predetermined energizing force; a second mount section which is provided separately from the first mount section and which can attach/detach a camera body having a power ON state of allowing photographing and a power OFF state of not allowing photographing thereto/from; a driven member which can move the diaphragm interlocking member in the photographic lens attached to the first mount section between the first and second positions against the energizing force; and drive means which performs, when the camera body mounted on the second mount section is in the power OFF state, drive control on the driven member to a retreat position where it is not in contact with the diaphragm interlocking member.