Recliner adjuster

A recliner adjuster for appropriately adjusting an inclination of a seat back with respect to a seat cushion includes a worm gear rotatably mounted on the seat cushion and a helical gear mounted on the seat back via auxiliary locking mechanism and held in engagement with the worm gear. During normal use, the seat back is held at a predetermined angle with respect to the seat cushion by the engagement of the helical gear with the worm gear. When a load greater than a predetermined value is inputted to the seat back, the auxiliary locking mechanism acts to hold the seat back at the predetermined angle with respect to the seat cushion.