An operation device (200) for wirelessly operating an X-ray imaging device (1) is held in a removable manner in a holder (100) included in the X-ray imaging device (1). The operation device (200) includes a control unit (211) that provides a notification when detecting that a predetermined condition is satisfied while the operation device (200) remains removed from the holder (100). This structure provides various notifications including a notification for preventing the operation device from being left or lost.
