An air spring for a vehicle may include a piston chamber with a bottom connected with an axle assembly to be able to move up/down, an air chamber with a top fixed to a car body and a bottom seated over a top of the piston chamber to be extendable and contractible by inflow/outflow of air, a piston positioned in the piston chamber, vertically dividing an internal space of the piston chamber into upper and lower internal spaces, and airtightly separating the upper internal space from the lower internal space, and an air control mechanism allowing air to flow into/out of the upper and lower internal spaces of the piston chamber and the internal space of the air chamber so that the piston chamber and the axle assembly are moved up/down with extension/contraction of the air chamber by the inflow/outflow of the air.