The present invention provides an airbag device that is capable of restraining a rectification cloth that switches a vent hole to an opened or closed state so as not to be twisted, and that is capable of switching the vent hole from an opened state to a closed state, and further, switching to the opened state. At an initial stage at which an airbag main body inflates and expands, the vent hole 8 is arranged between the leg portions 5, and when the airbag main body is in a predetermined internal pressure state, the vent hole is closed by means of the band-shaped portion 4. If an occupant or the like comes into contact with the airbag main body, a tense state of each of the leg portions is released, the rectification cloth is established in a slackened state, and the vent hole 8 is established in an opened state.