Airbag device

An airbag device to be applied to a vehicle, the vehicle being provided with

• a door provided to be openable and closable at a door opening provided on a side surface of a vehicle body of the vehicle, and
• a side sill disposed along a lower edge of the door, the airbag device comprising:
• an airbag configured to be deployed from a container to be disposed on a lower side of the door on the vehicle body to a region on a vehicle-widthwise outside of the door;
• and
• a pressure sensor configured to detect an air pressure in a space between an outer panel and an inner panel of the door, wherein
• the airbag comprises
• a first air chamber configured to transmit a load applied from the vehicle-widthwise outside to a side surface of the side sill,
• a second air chamber configured to couple, across a lower part of the first air chamber and the container and below the first air chamber,
• a valve provided at a vent channel that allows communication between an inside of the second air chamber and an outside of the second air chamber, and
• an internal pressure controller configured to:
• close the valve at a start of deployment of the airbag;
• determine, after the start of deployment of the airbag, whether the detected air pressure is equal to or higher than a preset threshold value;
• and
• in response to a determining that the detected air pressure is equal to or higher than the preset threshold value, open the valve.