In a vehicular seat device (20), a right seat (24) is movably supported via a right slide rail (21). The right seat is provided with a seat back (61) mounted to a movable base (31) of the right slide rail, a seat cushion (69) rotatably mounted to the seat back, and a connecting link (81) rotatably supporting a front portion (69a) of the seat cushion on the movable base. The connecting link includes a leg link portion (84) detachably supported on the movable base. The right seat when folded in a storage mode is movable to a storage position (13) of a lower floor (12).