The invention discloses an air compressor, comprising at least one air pump, wherein the air pump is internally provided with a piston and an air cleaner installed at an air inlet, and further comprising an electrical motor, wherein the electrical motor comprises a stator and a magnetic core yoke, the center of the stator is provided with a through hole, the wall of the through hole is provided with at least one set of stator cores vertical to the axle of the through hole, the stator core is provided with a magnetic coil, the magnetic core yoke is provided with magnetic steel above two pairs of electrodes, the N pole and the S pole of the magnetic steel are set in alternating manner, the magnetic core yoke is installed inside the through hole, one end of the magnetic core yoke is provided with at least one connecting bar connected with the piston of the air pump, and the magnetic core yoke is further provided with an elastic resetting device. The invention has the following advantage: the magnetic core yoke directly carries out reciprocating movement in the electrical motor to drive the piston by means of the advancement of the internal structure of the electrical motor, thereby efficiently improving the working efficiency, reducing the noises and prolonging the service life of the complete machine; and the reset position can be appointed by using the elastic resetting so as to conveniently re-start the air compressor.