Abstract: A self-adjusting control device for a flushing system mechanism borne by a stirrup and provided with pivoting arms actuated by fingers borne by pull-handles for flushing the water, the water flush control being provided via rods acting on the head of the pivoting arms, by externally accessible control knobs on the water flushing apparatus lid. The device comprises: a housing (16) containing the control knobs (19, 20), provided with a thread pitch (p1); an insert (14), integral in rotation with the housing (16) provided with a thread pitch (p2); a fitting (25) borne by the insert (14) carries the pivoting axis (26) of the arms (10, 11); the thread pitches (p1, p2) are in the ratio p1/p2 =L1/L2 of the vertical projections of the distances from the axis of the finger (33, 34) (L1) to the contact points (31, 32) of the heads (29, 30) of the arms (10, 11) and the rods (21, 22), and (L2) to the pivoting axis (26) of the arms (10, 11).