Disclosed herein is an asymmetrically expanding airbag cushion for a vehicle, which is inflated when airbag gas flows from an inflator through a gas hole to an interior of a cushion bag as a result of a vehicle collision. The airbag cushion includes a central expansion portion, a lower expansion portion and an upper expansion portion. The central expansion portion is provided on the central portion of the cushion bag to communicate with the gas hole. The lower expansion portion is surrounded by a lower sewing line which is open at a lower portion, and positioned under the central expansion portion. The upper expansion portion is surrounded by an upper sewing line which is open at an upper portion, and positioned above the central expansion portion. The central, lower and upper expansion portions are sequentially inflated when the airbag gas flows into the cushion bag.