PURPOSE: To obtain the captioned apparatus which is small-sized lightweight and which installation space can be secured easily, by installing a pair of cantilever leaf springs at right and left, separated each other between a cab and a chassis.

CONSTITUTION: A floating bar 1a on a cab 1 side is supported onto a rear arch 3 installed onto a chassis 2, through a cab suspension apparatus 4. In this case, a pair of cantilever leaf springs 5 installed in separated state in the direction of car width are installed onto the above-described apparatus 4. The main spring plate 5a of each cantilever leaf spring 5 is fixed onto a bracket 7 installed onto the rear arch 3 integrally with an auxiliary leaf spring 5b, by means of bolts 6 and the fixed edge 5c of the cantilever leaf spring 5. The eyelet part 5d at the other edge of the main leaf spring 5a is pivotally installed onto the pin 9 on the bracket 8 installed onto the floating bar 1a. Therefore, the apparatus is made small-sized and lightweight in comparison with the apparatus in which the conventional both-edge-supported leaf spring is used, and installation space can be easily secured.