The air compressor of the present invention comprises: a tubular outer casing (10); a fixed shaft (20) fixed to the outer casing (10); and a rotary sleeve (30) and an eccentric rotary body (40) supported with freedom to rotate on the fixed shaft (20). The fixed shaft (20) comprises: a central shaft (21) which is provided in the central part of the outer casing (10) and rotary sleeve (30), and which supports the rotary sleeve (30) in a rotatable fashion; and an eccentric shaft (22) which is provided in an eccentric position bending from the central shaft (21), and which supports the eccentric rotary body (40) in a rotatable fashion.