An adjusting screw (15) for a control lever device (1) for vehicles, wherein said adjusting screw (15) comprises a screw body (18) with a threaded shank (19) that can be screwed in a corresponding threaded hole (16) of the lever device (1) and a locking body (26) pivotally connected to the screw body (18). The locking body (26) comprises contact means (27) interacting with the screw body (28, 18) such as to counteract the rotation of the locking body (26) relative to the screw body (18) to a certain extent and anchoring means (29) engaging an anchoring seat (17) of the lever device (1) such as to prevent that the locking body (26) may rotate relative to the threaded hole (16) of the lever device (1). There are also provided means (25) for preventing that the locking body (26) may be displaced along the shank (19) of the screw body (18).