Included are: a first supporting member; a second supporting member arranged to be spaced away from the first supporting member in a main load direction; an elastically deformable diaphragm forming a closed space by connecting the first supporting member and the second supporting member; a detection unit detecting a change of a relative distance between the first supporting member and the second supporting member, and producing a mechanical output of the change of the relative distance; and a controlling member capable of discharging air in an inside of the closed space S to an outside of the closed space S in response to the mechanical output from the detection unit. Thereby, an air spring having a mechanism for suppressing an abnormal rise of a vehicle height without deteriorating the diaphragm can be provided.