A connecting cable device includes a cable having two connectors attached to two end portions of the cable, and a lock device includes an elongated member, a casing formed on one end portion of the elongated member and having a chamber formed in the casing for engaging with the cable, a blocking member is engaged into the chamber of the casing for enclosing the chamber of the casing and for engaging with the cable and for retaining the cable in the chamber of the casing, and a fastening element is engaged with the casing and the blocking member for locking the blocking member to the casing and for preventing the blocking member from being disengaged from the casing.