To make it possible to relax the tension the lumbar vertebrae, when necessary, at a seated position on a seat.
The seat of automobile has a lumbar support structure mounted inside a seat back to support the lumbar vertebrae of a seater. The lumbar support structure 2 comprises a lumbar plate 22 corresponding to the lumbar vertebrae of the seater and a position changing mechanism 3 changing the position of the lumbar plate 22 inside the seat back between a front position where it is advanced to support the lumbar vertebrae and a rear position to which it is retreated so as not to support the lumbar vertebrae. The position changing mechanism 3 includes a damper device 76 by which the lumbar plate 22 set in the rear position is gradually restored to the front position.
KAWASHIMA YOSHIHITO
OKAMOTO NOBUHISA
MAZDA MOTOR