An adapter includes: a first mount section that is detachably attached to a camera body; a second mount section that is provided separately from the first mount section and is detachably attached to an interchangeable lens; and a power supply section that generates supply voltages of a third power supply system and a fourth power supply system, which are to be fed to the interchangeable lens mounted on the second mount section, from a second power supply system between a first power supply system of the camera body, which is mounted on the first mount section, and the second power supply system which is different from the first power supply system.