An anti-unlock screw device (100) for connector designed to maintain the connection between two connection elements (1, 2), includes a cylindrical sleeve (101) provided with a row of saw-tooth notches (105) arranged on an internal circumference of a rear portion. The device also has an internal ring (106) mounted in the rear portion of the cylindrical sleeve so that it can be positioned between the cylindrical sleeve and the first connection element, the internal ring including at least one catch (107) capable of cooperating with the saw-tooth notches of the cylindrical sleeve. A blocking device (110, 111, 112, 113) keeps the internal ring fixed relatively to the cylindrical sleeve in a first sense of rotation (V) and inversely keeps the internal ring free in rotation relatively to the cylindrical sleeve in a second sense of rotation (DV).