To provide a pneumatic shock absorber capable of suppressing a change in the height of a vehicle due to a change in the temperature of the inside of the shock absorber, smoothly extensible, and suppressing the degradation of a seal member.

This pneumatic shock absorber D includes a cylinder C, a piston P slidably inserted into the cylinder C, and a rod R connected to the piston P and movably inserted into the cylinder C. The pneumatic shock absorber is interposed between a vehicle body and an axle, and damps the relative movement of the vehicle body to the axle. The shock absorber further includes a supply/discharge means 3 for supplying and discharging a gas into and from the cylinder C.