Abstract: A hard diskdrive mobile rack formed of a hollow rack, a top cover and a buffer unit for mounting in the mainframe of a computer to carry a hard diskdrive for storing data, wherein the rack body has an opening for the loading of a hard diskdrive, and an electric connector for connection to the circuit of the mainframe of the computer; the top cover is slidably inserted into the rack body to close the opening of the rack body; the buffer unit includes a tray, which carries the loaded hard diskdrive, and a plurality of spring elements, which support the tray and the loaded had diskdrive in the rack body to eliminate shocks.