To make an inclined angle of an axle become almost zero even if a leaf spring or the like vertically strokes.

The air suspension device is equipped with the leaf spring 4 which is supported by the axle 2 supporting a wheel 3, and extended to the longitudinal direction of a vehicle, and an air spring 6 which is offset to the rear side of the longitudinal direction of the vehicle than the axle 2 and supported by the axle 2 through the leaf spring 4. The air suspension device is constituted so that an off-set ratio of the ratio between a horizontal direction distance Lb from the axle 2 to a horizontal pin 13 and an offset amount Lo from the axle 2 of the air spring 6, and a spring characteristic ratio of the ratio between a spring constant of the leaf spring 4 in the front direction of the vehicle from the axle 2 and the spring constant of the leaf spring 4 in the rear direction of the vehicle from the axle 2 are set to be a predetermined value.