A vehicle seat device comprising: a base member (32, 33) which is provided in one of a seat cushion (2, 102) and a seat back (3, 103); a movable member (33, 34) which is rotatably connected to the base member (32, 33); and a pair of stopper parts (56, 57, 66, 67) which are disposed so as to abut against each other on the base member (32, 33) and the movable member (33, 34), wherein the movable member (33, 34) is configured to rotate in a deployment direction which is one direction from a storage position, with respect to the base member (32, 33), and the rotation of the movable member is restricted at a deployment position at which both the stopper parts (56, 57, 66, 67) abut against each other so that a seat mode is changed, and the vehicle seat device further comprises an air bag (59, 69) which is interposed between the base member (32, 33) and the movable member (33, 34) and configured to press the base member (32, 33) and the movable member (33, 34) as the air bag (59, 69) is inflated to rotate the movable member (33, 34) from the storage position toward the deployment position; characterized in that a clutch mechanism (55, 65) is interposed between the base member (32, 33) and the movable member (33, 34), configured to allow the rotation of the movable member (33, 34) in the deployment direction, and to restrict the rotation of the movable member (33, 34), which is located at the deployment position, in a storage direction opposite to the deployment direction. a base member (32, 33) which is provided in one of a seat cushion (2, 102) and a seat back (3, 103); a movable member (33, 34) which is rotatably connected to the base member (32, 33); and a pair of stopper parts (56, 57, 66, 67) which are disposed so as to abut against each other on the base member (32, 33) and the movable member (33, 34), wherein the movable member (33, 34) is configured to rotate in a deployment direction which is one direction from a storage position, with respect to the base member (32, 33), and the rotation of the movable member is restricted at a deployment position at which both the stopper parts (56, 57, 66, 67) abut against each other so that a seat mode is changed, and the vehicle seat device further comprises an air bag (59, 69) which is interposed between the base member (32, 33) and the movable member (33, 34) and configured to press the base member (32, 33) and the movable member (33, 34) as the air bag (59, 69) is inflated to rotate the movable member (33, 34) from the storage position toward the deployment position; characterized in that a clutch mechanism (55, 65) is interposed between the base member (32, 33) and the movable member (33, 34), configured to allow the rotation of the movable member (33, 34) in the deployment direction, and to restrict the rotation of the movable member (33, 34), which is located at the deployment position, in a storage direction opposite to the deployment direction. an air bag (59, 69) which is interposed between the base member (32, 33) and the movable member (33, 34) and configured to press the base member (32, 33) and the movable member (33, 34) as the air bag (59, 69) is inflated to rotate the movable member (33, 34) from the storage position toward the deployment position; characterized in that a clutch mechanism (55, 65) is interposed between the base member (32, 33) and the movable member (33, 34), configured to allow the rotation of the movable member (33, 34) in the deployment direction, and to restrict the rotation of the movable member (33, 34), which is located at the deployment position, in a storage direction opposite to the deployment direction.