The present invention is to provide a card reader that can prevent the illegal acquisition of magnetic information recorded on a magnetic stripe, based on an output signal from a pre-head. More specifically described, in a card reader having a card insertion slot for guiding a magnetic card having a magnetic stripe to a transport passage and a pre-head arranged in the vicinity of the card insertion slot for detecting the presence of the magnetic stripe, the pre-head is equipped with a head portion having at least one pair of magnetic cores arranged to be opposite from each other having a magnetic gap between them and coils wound around a pair of the magnetic cores; and a signal different from that of the magnetic information recorded on the magnetic stripe is output from the pre-head.