a seat adjuster is disclosed , which comprises a seat pan ; parallel first and second base members ; spaced first and second rod members , each being rotatably supported by the base members ; first and second link mechanisms respecitvely connected to the first rod member and mounting thereon a front part of the seat pan , the first and second link mechanisms raising the front part of the seat pan when the first rod member is rotated about its axis in a given direction ; third and fourth link mechanism respectively connected to the second rod member and mounting thereon a rear part of the seat pan , the third and fourth link mechanism raising the rear part of the seat pan when the second rod member is rotated about its axis in a given direction ; and first and second drive mechanisms mounted to the first base plate for turning the first and second rod members respectively . each drive mechanism has a one - way clutch function which locks parts of the drive mechanism when a torque is applied thereto from the associated rod member . the first rod member has a sector gear connected thereto and operatively engaged with the first drive mechanism . the sector gear is positioned at an opposite side of the second drive mechanism with respect to the first drive mechanism .