A vehicular seat arrangement for use in an automotive vehicle, comprising at least two seat assemblies positioned on the floor panel in parallel with each other laterally of the vehicle body, each seat assembly having a seat cushion portion and a seat back portion upstanding from the seat cushion portion and rockable with respect to the seat cushion portion about a pivot axis in a lateral direction of the seat assembly, a seat reinforcing device including an elongated reinforcement member extending in a lateral direction of the vehicle body between the side wall portions of the vehicle body and passed in part through the seat back portion of one of the seat assemblies and in part through the seat back portion of the other of the seat assemblies, and tilt regulating means permitting the seat back portion of one of the seat assemblies to tilt with respect to the seat cushion portion of the seat assembly about the pivot axis independently of the seat back portion of the other of the seat assemblies.