AIRBAG DEVICE

[PROBLEM] To provide an airbag device that can reliably expand and deploy. [MEANS FOR SOLVING THE PROBLEM] The present invention is an airbag device mounted on one side of a vehicle seat in which both ends of a seat-shaped cushion that are opposed in horizontal and longitudinal directions during expansion and deployment are respectively bent a plurality of times and formed into molded parts R, R, and is provided with a first holding member that holds the first molded part R on one end of either of the ends at least until the start of expansion and deployment and a second holding member that holds the second molded part R on the other end at least until the start of expansion and deployment.