Side airbag device for vehicle

A side airbag device for a vehicle comprising:

• an inflator that generates gas by activating;
• an airbag that is provided at a side portion of a seatback of a vehicle seat, the airbag inflates and expands toward a vehicle front side of the side portion due to gas being supplied to an interior of the airbag by the inflator, the airbag being configured to retrain at least from a chest portion to a head portion of a vehicle occupant located in the vehicle seat;
• and
• a partitioning portion that partitions the airbag into:
• (i) a rear bag portion that restrains at least a rear portion of the chest portion of the vehicle occupant, and (ii) a front bag portion that restrains a front portion of the chest portion of the vehicle occupant, the partitioning portion including:
• a laterally extending portion extending toward a front side of the seatback from a vertical direction intermediate portion of a rear end portion of the airbag that has inflated and expanded;
• a vertically extending portion extending toward an upper side of the seatback from a longitudinal direction intermediate portion of a lower end portion of the airbag that has inflated and expanded, and,
• a plurality of communication ports formed at the partitioning portion to supply gas from the inflator that is accommodated within the rear bag portion into the front bag portion.