A vehicular seat device comprising a seat, an inner rail, an outer rail and a movable base, the outer rail being provided outside of the inner rail in a width direction of a vehicle body, the inner rail and the outer rail being securable to a high level floor of a vehicle body floor and extending in a front-rear direction of the vehicle body, the movable base being provided on the inner rail and the outer rail so as to be movable with respect to the high level floor, the seat being provided on the movable base, and the seat being supported by the vehicle body floor such that the seat is movable in the front-rear direction of the vehicle body, wherein the seat comprises: a seatback provided on the movable base such that the seatback is pivotable in the front-rear direction of the vehicle body; a seat cushion having a rear portion supported by the seatback such that the seat cushion is pivotable about the rear portion of the seat cushion in the front-rear direction of the vehicle body; and a connection link having a lower end portion which is positioned between the inner rail and the outer rail in the width direction of the vehicle body, and the connection link lower end portion being detachably supported by the movable base, the seat cushion having a front portion supported by the movable base through the connection link such that the front portion of the seat cushion is movable in the front-rear direction of the vehicle body, wherein the seatback is forwardly pivotable to overlie the seat cushion, wherein the movable base includes a link supporting section provided therewith, the link supporting section being positioned between the inner rail and the outer rail in the width direction of the vehicle body, and the link supporting section being provided to detachably support the lower end portion of the connection link, and wherein the seat is movable to a stowing location of a low level floor of the vehicle body floor with the seatback overlying the seat cushion. a seatback provided on the movable base such that the seatback is pivotable in the front-rear direction of the vehicle body; a seat cushion having a rear portion supported by the seatback such that the seat cushion is pivotable about the rear portion of the seat cushion in the front-rear direction of the vehicle body; and a connection link having a lower end portion which is positioned between the inner rail and the outer rail in the width direction of the vehicle body, and the connection link lower end portion being detachably supported by the movable base, the seat cushion having a front portion supported by the movable base through the connection link such that the front portion of the seat cushion is movable in the front-rear direction of the vehicle body, wherein the seatback is forwardly pivotable to overlie the seat cushion, wherein the movable base includes a link supporting section provided therewith, the link supporting section being positioned between the inner rail and the outer rail in the width direction of the vehicle body, and the link supporting section being provided to detachably support the lower end portion of the connection link, and wherein the seat is movable to a stowing location of a low level floor of the vehicle body floor with the seatback overlying the seat cushion.