Abstract: A pneumatic nail driver includes a main body having a cavity defined for receiving a spring and a sleeve that has an annular groove defined in an outer periphery of the sleeve. A passage is defined in the main body and selectively communicates with the annular groove for allowing the compressed air flow into the sleeve. A block and a cylinder are sequentially received in the cavity. A striker is reciprocally movably received in the cylinder due to the block and the compressed air. A shaft partially longitudinally extends into the cylinder and the striker is moved to strike the shaft for driving the nail when the shaft and the cylinder are backward pushed to make the annular groove communicate the passage to guide the compressed air flowing to the cylinder for pushing the striker.