A mounting apparatus on which an accessory including a first mount is mountable, comprising: a second mount that is capable of coupling to the first mount of the accessory; terminals disposed along a circumferential direction of the second mount and used for electrical connection with corresponding terminals provided on the accessory; and mount claws for engaging with claws provided in the accessory. A terminal holder has first and second stages at different positions in a direction parallel to a center-axis direction of the second mount. The terminals include a first terminal for detecting mounting of the accessory and a second terminal for supplying communication power to the accessory. The second stage is projecting toward the accessory further than the first stage in a state where the accessory is mounted on the mounting apparatus.