A curtain airbag for a vehicle may include a curtain airbag cushion divided into an upper cushion and a lower cushion, a folding portion at the upper cushion, and a door panel tether having a first end fixed to the folding portion and a second end fixed to a car body, in which when the curtain airbag inflates, a door side of the upper cushion may be pressed by the tension of the door panel tether and the upper cushion turns inward.