A rack-mounted device includes a case configured to include, in a width direction, a plurality of containment rooms each in which an electronic device is contained, a partition suspended from an upper wall of the case and configured to partition off the plurality of containment rooms adjacent to each other and guide the electronic device, and a support plate extending from a sidewall of the case into a containment room of the plurality of containment rooms and provided with a gap from a lower wall of the case to support the electronic device.