Abstract: A seat apparatus for a vehicle includes a seat portion having a seat cushion, a seat slide mechanism for adjusting the position of the seat portion back and forth, and a lock mechanism adapted to effect locking engagement of the seat portion with a striker fixedly arranged relative to the floor of the vehicle, with the locking engagement being adapted to be released at a predetermined fixed position of the seat portion. A first operational mechanism is provided for operating the lock mechanism and is adapted to be operated from the rear side of the seat portion, and a second operational mechanism is provided for adjusting the position of the seat portion and is adapted to be operated from the front side and the rear side of the seat portion.