The expandable telescopic baton (1) consists of the handle (2), the central tube (5) with secondary locking member, of the end tube (6) with terminal locking member, of the button (4) and of the release rod (8). The locking member comprises at least two lever segments of the first order (9, 9′), whose first tilting arms (11) bear the radial projections (10) securing the tubes (5, 6) in the extended position, the second tilting arms (12) extend inside the tubes (5, 6), and the tilting means comprising the tilting edge (15) ensures the tilting of the segments (9, 9′) against the inner wall of the tube (5, 6). The release rod (8) passing through the locking tilts over the segments (9, 9′), thus extending radial projections (10) from the internal radial grooves (7, 7′).