SEAT AIRBAG FOR VEHICLE

A seat airbag for a vehicle is installed in a side part of a seat back and an airbag cushion (100) thereof is deployed forward. A front portion of the cushion is divided into a head chamber (140) disposed at an upper location, a chest chamber (160) disposed at a central location and a pelvis chamber (180) disposed at a lower location. The airbag protects a vehicle occupant while wrapping around the occupant with use of a first tether to a fourth tether (T1-T4) that are integrally formed into a single string and connect the respective chambers to each other.