To prevent the air leak of an air chamber of an air spring by preventing a supporting member of the air spring provided between a beam mounted on an axle case and a car body frame from interfering with the beam.

An air spring 60 is provided between the end part of a beam 24 mounted on an axle base and a car body frame 2. A relief part 82 is formed between the lower end part of a housing part 68 constituting a piston 85, namely the supporting member of the air spring 60 and the beam 24 so that the beam 24 does not interfere with the housing part 68 when the beam is bent-deformed. Thus, the housing part 68 is not subjected to damage even when it collides with the beam 24. Besides, auxiliary air chambers 69 in the housing part 68 which are connected to the air chamber 66 in a diaphragm 63 through connecting holes 73 are kept airtight.