PURPOSE: To always exhibit excellent damping effect by continuously changing the size of restriction by vibration.

CONSTITUTION: This air spring device of which the air spring 3 is used as a secondary spring of a railway rolling stock and the air spring main body and the auxiliary air chamber are communicated to each other through a restriction, is constituted of a variable restriction mechanism 8 to continuously change the size of restriction. Thereby, optimum damping force due to the skyhook damper theory can be continuously obtained, and vertical vibration of the body of the railway rolling stock can be efficiently restrained by means of a relatively simple mechanism of a little energy consumption.