The present invention provides a lock structure of plug of cable including a main body and a key. The main body has a locking area, an elastic area with an elastic element, and a lower room which is able to receive a plug of cable. The elastic element tends to stay at a first position. When the key is not inserted into the locking area, the elastic element is at the first position, and a latch of the plug of the cable is unable to be compressed due to the fixation by the elastic element. When the key is inserted into the locking area and is rotated, the elastic element is pushed to a second position, and the latch is able to be compressed. Thereby, the lock structure of plug of cable can be used to control the availability of the plug for a jack.