Vehicle seat with backrest deformation

The vehicle seat has a seat portion (2) that is provided with a seat cushion surface portion (4). The backrest cushion surface portions (5,5a) of a backrest (3) are formed on a base frame (1). The lower portion (1a) of the base frame is attached with a bow-like element (8) with two end regions (8a,8b) and a central portion (8c). A seat unit (9) is arranged in the longitudinal direction of the base frame. The backrest cushion surface portion in the lower region (6b) is lifted by the pivoting movement in the forward direction of seat portion.