The recognition rate is improved while suppressing the processing time. The character recognition unit 80 of a check reader 1 uses two sets of reference waveform data, data for printing method 1 and data for printing method 2, in combination with modifying the reference waveform data in two ways, sliding the reference waveform data or scaling the reference waveform data according to variation in the line width of the magnetic ink character 101, to execute four candidate selection processes. If the same character is selected as a candidate by the first three of the four selection process combinations, the remaining one of the four processes is limited to using the reference waveform data for the selected candidate character.