A magnetic information processing device for use with a magnetic recording medium storing a magnetic signal may include a magnetic card detection unit comprising a sensor and being structured to detect insertion of the magnetic recording medium; a magnetic head structured to read the magnetic signal recorded in the magnetic recording medium, and output the magnetic signal as an analog signal; a signal detection unit structured to amplify the analog signal output from the magnetic head, and output a detection output signal when the analog signal exceeds a predetermined threshold value of a magnetic detection sensitivity; and a judgment unit structured to judge that the detection output signal output by the signal detection unit is different from the magnetic signal recorded in the magnetic recording medium, when no insertion of the magnetic recording medium is detected by the magnetic card detection unit.