To provide an air spring capable of reducing a dynamic spring constant and improving ride comfort of an automobile while having a structure wherein height dimension of a piston is shortened and weight is reduced.

This air spring is provided with a cylindrical diaphragm 1, a disk-shaped upper plate 2 and the cylindrical piston 3. A lower end part 9 of the diaphragm 1 is folded inwardly and covers the piston 3, and the diaphragm 1, upper plate 2 and piston 3 are concentrically arranged. The lower end part 9 of the diaphragm 1 is folded inwardly and covers only an upper end part 7J side of the piston 3, and the diameter of the upper plate 2 is set smaller than that of the piston 3.