SEAT-MOUNTED AIRBAG DEVICE

A seat-mounted airbag device includes an inflator, an airbag body, and a guide member. The airbag body includes a front-rear chamber and a tip chamber. The front-rear chamber is deployed forward of a seat through a clearance between a window and a head of an occupant from a side portion of a headrest on a window side by gas ejected from the inflator and disposed between the window and the head of the occupant. The tip chamber is deployed inward in a seat width direction from an end portion of the front-rear chamber on a seat front side and disposed forward of a face of the occupant on the seat front side. The guide member protrudes from the side portion prior to deployment of the airbag body and is interposed between the airbag body and the head of the occupant.