Provided is to stabilize a fixed state of each bag body provided at a vehicle seat and configured to expand to push a corresponding one of the shoulders of a seated passenger. Of a seat back provided at the vehicle seat, each shoulder support configured to support a corresponding one of the shoulders of the seated passenger includes an air cell configured to expand by injection of air. The air cell includes protrusions extending in a predetermined direction and provided at respective end portions of the air bag in the extending direction thereof. The air cell is attached to the inside of the seat back in such a manner that each of the protrusions provided at respective end portions in the extending direction is fixed to a corresponding one of fixing positions separated from each other in the width direction of the vehicle seat.