The interval between the read head and the dummy head is used a narrow differential equation skimming magnetic head of to provide a card reader capable of blocking skimming by skimming magnetic head of the differential type. This card reader, the disturbing magnetic field generating unit 10 includes a core 11 having a first end face 11a and a second end face 11b which is arranged so as to face substantially front side, the direction of magnetic field lines ML1 from the first end face 11a It is generating disturbing magnetic field that varies in a direction and a second end surface 11b toward the second end face 11b in the direction toward the first end surface 11a. The disturbing magnetic field of the magnetic field lines ML1, direction exiting from one of the first end face 11a and a second end face 11b, and, the direction coming into the other one of the first end face 11a and a second end surface 11b, the card 2 It is substantially parallel to the passage direction. Further, magnetic field lines ML1, in the width direction of the card 2, crosses the position where the magnetic stripe 2a passes.