To provide a technique that is effective for allowing a pressurized fluid to pass through smoothly between a plurality of bag-like bodies when inflated and extend, and for improving their extendibility.An airbag device includes a first bag 35 composed of a bag body formed by joining base fabrics 35A, 35B, and provided with a supply flow passage for supplying a pressurized fluid supplied from an inflator into the inside and a flow-out passage for allowing the pressurized fluid supplied into the inside to flow out to the outside, a second bag 36 composed of a bag body formed by joining base fabrics 36A, 36B, and provided with a flow-in passage for allowing the pressurized fluid allowed to flow out from the flow-out passage of the first bag 35 to flow into the inside, and a connection panel PN for connecting the first bag 35 and the second bag 36 so that the whole of the first bag 35 and the second bag 36 is configured in a predetermined shape when inflated and extends.