A vehicle seat includes a seat back, an inflator, and a side airbag. The side airbag includes a head chamber housed along an upper frame of the seat back and configured to inflate and deploy between a shoulder belt and a head in response to supply of gas from the inflator in an event of side collision. The head chamber is housed while being folded in a seat up-and-down direction to reduce a vertical width and then rolled from a front end in a seat fore-and-aft direction.