A storage device includes a memory module including a memory device, a module board including a memory controller configured to control the memory device, and a memory connector disposed on one side of the module board. The storage device also includes a first enclosure disposed on a first surface of the memory module, a second enclosure disposed on a second surface opposite to the first surface of the memory module, and a first sensor disposed on the first enclosure and configured to detect a state and provide a signal for the state to the memory controller. The first enclosure includes a first long side extending in a first direction and a first short side extending in a second direction perpendicular to the first direction. A ratio of the first long side to the first short side ranges from 1.2 to 3.5.