<p>A double lock seat recliner has a primary recliner device and a secondary recliner device are connected by a rotary linking rod. A first lever (18) pivotally mounted on a pivot of a release lever. A second lever (17) is connected with the first lever (18) by means of a connecting pin. The second lever (17) is cooperated to the rotary linking rod (16). A third lever (17a) is pivotally cooperated with the rotary lever. A fourth lever (18a) is pivotally connected to the third lever (17a) via a connecting pin. The fourth lever (18a) is cooperated with a pivot shaft of a locking member of the auxiliary recliner device. The third lever (17a) is mounted on the inner side of a base plate (1a). On the other hand, the fourth lever (18a) is mounted on the out side of the base plate (1a). The connecting pin (21) for cooperably connecting the third lever (17a) with the fourth lever (18a) extends through an elongated slot formed through the base plate (1a).</p>