An object of the present invention is to ensure smooth deployment of an airbag having a turned-back end portion. The present invention is an airbag device that expands and deploys in a curtain shape on a side portion of a vehicle interior in order to protect an occupant of the vehicle interior, where the airbag includes a gas generator for generating an expansion gas and an airbag that deploys when it is expanded by the gas supplied from the gas generator. The airbag is compressed into an elongated shape when stowed and an end portion of the elongated airbag is turned back in a lengthwise direction, thereby forming an airbag main portion that is not turned back and the turned-back end portion. A restricting member is also provided to restrict deployment of the turned-back end portion of the airbag toward a vehicle outer side when the device is activated.