Disposed is a seat device wherein a first seat cushion (41) of a first seat (16) is sprung up from a seating position to an upright folded position at a location forward of the seating position. The seat device (15) comprises first vertical leg sections (51, 52) at the front of the first seat cushion (41), these vertical leg sections (51, 52) extending vertically downward. First horizontal sections (54, 55) extend horizontally forward from the lower ends of the first vertical leg sections (51, 52), and are rotatably connected to a first slider (48) which is slidably connected to a fixed rail (35). In the seating position of the first seat cushion (41), the lower ends of the first vertical leg sections (51, 52) are supported by the floor.