In a vehicular seat 10 according to this invention, since a back shell 32 covers a back frame 31, as in the case where the shape of a seat back is formed of the urethane pad, the shape of the seat back is not easily changed. Thus, the passenger can be surely held. Further, since the back shell 32 is displaceably supported for the back frame 31, the back shell 32 is displaced according to the figure or posture of the passenger. This permits the passenger to sit with good riding comfort.