Vehicle occupant protection device

A vehicle occupant protection device comprising:

• a vehicle seat belt device containing a seat belt configured to restrain an occupant seating on a vehicle seat;
• an airbag which is provided on the seat belt in a folded state and in which the inside of an upper bag portion for restraining a head communicates with the inside of a lower bag portion for restraining a chest and an abdomen via a communicating portion;
• and
• an inflator which supplies gas into the lower bag portion when activated, wherein
• the vehicle seat belt device is of three-point type,
• the airbag is provided on a lap belt of the seat belt,
• the communicating portion is provided with a check valve which allows a flow of gas from the inside of the lower bag portion to the inside of the upper bag portion and limits the flow of gas from the inside of the upper bag portion to the inside of the lower bag portion,
• when the lower bag portion is compressed by the chest and the abdomen of the occupant being inclined forward, the upper bag portion is expanded,
• the upper bag portion is expanded behind the lower bag portion being expanded because gas from the inflator is supplied to the upper bag portion through the lower bag portion, and
• the upper bag portion is completely expanded when the lower bag portion is compressed by the chest and the abdomen of the occupant being inclined forward and gas in the lower bag portion is pushed out to the upper bag portion, and then the airbag is completely expanded when the inflator supplies gas to the lower bag portion additionally.