An automobile seat assembly includes a seat cushion subassembly and a seat back subassembly coupled with the seat cushion subassembly to represent a generally L-shaped configuration. A holding device is installed in the seat cushion subassembly and is deformable in response to the sitting of a seat occupant on a sitting area of the seat cushion subassembly and holds the sitting area in a deformed shape resulting from the seat occupant sitting on the sitting area. An actuating device installed in the seat cushion subassembly actuates the holding device. A detecting device detects the actual sitting position of the seat occupant on the sitting area. A control device is operable to operate the actuating device a predetermined time after the detecting device has detected the actual sitting position of the seat occupant on the sitting area.
