A side curtain airbag for a vehicle includes an inner panel facing an interior of the vehicle, an outer panel facing the inner panel, a stopper chamber configured to prevent a head of an occupant seated on the vehicle from being moved toward a front side of the vehicle, a forward chamber arranged at a front side of the stopper chamber, and a rearward chamber arranged at a rear side of the stopper chamber. The forward chamber and the rearward chamber are arranged to be adjacent to each other such that in a non-inflation state of the airbag, a portion in which the stopper chamber is located is folded at least one time to form an overlapped portion.