An air compressor structure includes a cylinder, a piston, a cylinder lid, and a pressure gauge. The piston coupled in the cylinder performs reciprocating motion to generate compressed air, and the cylinder lid is assembled to the cylinder to receive the compressed air. The pressure gauge includes a propelling barrel movably disposed in the cylinder lid and having a gear rack, a value panel disposed on a surface of the cylinder lid, a pointer, and a spring disposed in the cylinder lid and abutting against the propelling barrel. The pointer includes a pointing portion and a pivot, where the pivot is disposed on the cylinder lid and has a gear engaged to the gear rack, and the pointing portion extends from the pivot and is located on the value panel.