VEHICLE SEAT

Weight reduction is realized and vibration absorbability and impact absorbing properties are improved. A vehicle seat 1 of the present invention includes a tension structure extended on a back frame 10 and has a configuration in which a natural frequency in the right-and-left direction of the back frame 10 is set lower than the natural frequency in the front-and-rear direction. Since the natural frequency in the right-and-left direction is lower than the natural frequency in the front-and-rear direction, the structure can easily deflect in the right-and-left direction. Therefore, since an impact load larger than a predetermined level inputted in the front-and-rear direction due to front-and-rear/pitching vibration or a rear collision and the like becomes a force of deflecting the back frame in the right-and-left direction, the vibration/impact energy is consumed by that, and moreover, rearward displacement of the back frame consumes vibration/impact energy. Thus, absorbing performances of the vibration/impact energy are higher than before.