A lateral airbag device comprises a gas bag which is mounted in a vehicle seat below the seat covering of the vehicle seat. The gas bag is inflated in the event of an accident. The seat covering comprises at least one break line, which can be torn open when the gas bag unfolds enabling the gas bag to exit the vehicle seat. The lateral airbag device is capable of protecting the occupants of a vehicle in the event of an accident in a reliable manner. The seat covering is configured to bring the unfolding gas bag to a predetermined position or to maintain the unfolded gas bag in the predetermined positioned.