OCCUPANT RESTRAINT DEVICE

An occupant restraining device that can be reliably expanded and deployed is provided.An airbag (3) provided on the side portion of a vehicle seat backrest portion (4) and a tensile cloth (2a) that biases the expanding and deploying airbag (3) toward an occupant (P) sitting in the vehicle seat are included. A first end (21a) of the tensile cloth (2a) is retained by an engage position of an upper part of the backrest portion (4) and a second end (22a) is retained by a prescribed location of the vehicle seat. The tensile cloth (2a) is joined to the surface of the airbag (3) using a joint portion (23a, 24a) in at least one location. With the folded airbag (3) stowed in the vehicle seat, a first distance (L1) between the engage position along the outer shape of the backrest portion (4) from this engage position to the furthermost joint portion (23a) is shorter than a second distance (L2) along the outer shape of the backrest portion (4) from the engage position to the center of rotation of the shaft (6) that movably retains the backrest portion (4).