PURPOSE: To make improvements in the durability and reliability of an air spring device, in this cab air suspension available in those of cab-over type motor trucks and tractors, etc.

CONSTITUTION: A lower seat member 34 of an air spring device 30 is secured to a member at the side of an undercarriage frame, for example, a connecting arm 24 by a threaded pin 44 and a nut 46 projectingly installed in this seat member after positioning it in all directions in addition to fall-off stopping. Simultaneously with this, an air inlet 48 installed in the lower seat member 34 is engaged with a recess or notch 50 installed in a member at the undercarriage frame side, whereby the whirl-stop of this lower seat member 34 takes place.