A lockable storage device includes a main body defining a connector; and a locking mechanism including a stopping member and a driving plate assembly. The connector defines a receiving space for receiving a port, the stopping member is movable in the receiving space. The driving plate assembly includes a number of driving plates marked with numbers. When a combination of numbers, formed by surfaces which are on a same plane, is different from a predetermined number sequence, the storage device is locked, when the combination of numbers formed by the surfaces is the same as the predetermined number sequence, the storage device is unlocked.