The lens driving adapter is detachably attachable to a lens barrel on which an operation member is provided. The adapter includes a driver configured to drive the operation member, and an adapter body holding the driver. The adapter body includes a first contact portion and a second contact portion that are protrusions contactable with two circumferential portions in an outer circumferential surface of the lens barrel. The first and the second contact portions are contactable with outer circumferential surfaces of lens barrels whose outer diameters are mutually different. The adapter body includes a fixing member configured to fix the adapter body to any of the lens barrels.