An accessory mounting device and system for the same, particularly involving radiographic systems, includes a feature to securely recognize a fixing condition of an accessory. In mounting a platform to a table, a fixing member is oscillated or moved so that the platform moves to an engagement position. A pin installed at a tip of the fixing member engages a fixing element formed in the table. Then, a movement restriction member is oscillated so that it can move to a restriction position. An oscillating movement of the movement restriction member is restricted by moving a lock-pin. Alternatively, a fixing member in a movable non-lock-state allows a display region recognizable from a display position.
