To improve the read precision of magnetic characters with a small and inexpensive device by comparing results stored in a 1st storage means which stores magnetic characters as the length of a character string and a 2nd storage means which stores optically read characters as the length of a character string.

The magnetic detection signal of a detector 6 is sent to a read part 15, which finds and inputs a magnetic change point at the head character end and a magnetic change point at the tail character end of magnetic characters to a gate A in the form of a signal. Similarly, the optical detection signal of a detector 7 is sent to a read part 18, which finds and inputs change points of optical reads of the head character end and tail character end to a gate B in the form of a signal. A comparator 22 compares the lengths of character strings by the magnetic detection and optical detection with each other and judges that information of the detector 6 or 7 is improper when there is a large difference in the number of blocks, so that the process result will not be sent to a control part.