A compact simplified compressor apparatus is provided with a rotating shaft rotationally driven by a motor, a compact compressor activated by the rotating shaft, an air feeding means for feeding a high-pressure air from the compact compressor to a tire, and a power source plug supplying an electricity to the motor. The compact compressor is provided with a rod attached to the rotating shaft via a crank, a piston having a peripheral groove in an outer peripheral surface and integrally formed with the rod, a cylinder having a cylinder chamber receiving the piston so as to freely reciprocate, and a ring seal sealing between the piston and an inner peripheral surface of the cylinder chamber. The ring seal is provided with a base portion having a base surface seating on a groove wall surface in the rod side of the peripheral groove, and inner and outer lip portions, each extending from the base portion toward radially inside and outside so as to be opened toward the opposite rod side.