To provide a cushion supporting structure capable of avoiding any increase of the component number and the weight and any complication of the structure while ensuring the cushion stroke length.

In the cushion supporting structure, right and left wheels are independently suspended by a frame via suspension arm in a rocking manner, and a drive shaft for transmitting the power from an engine to each wheel is provided. The suspension arm is formed of upper and lower arms 82, 83, a knuckle 84 is supported by the upper and lower arms 83, 84. The knuckle 84 rotatably supports the wheels, and a cushion 80 absorbs the shock transmitted to the wheels. A lower end of the cushion 80 is coaxially supported by a knuckle supporting part 110 of the lower arm 83.