A storage device suitable to be installed on a rack includes a case, a plurality of storage units, a power module, a management module and an adapting board, wherein the case includes a bottom board, a first side wall, a second side wall and a partition board. The partition board is located over the bottom board to divide the case into an upper and a lower accommodation spaces. The storage units are disposed in the upper accommodation space and the power module is disposed in the lower accommodation space. The power module includes a power backboard and power suppliers plugged at the power backboard. The management module disposed in the lower accommodation space has an expanding interface. The adapting board is disposed in the lower accommodation space and electrically connected to the power backboard, the management module and the storage units.