PURPOSE: To read even characters, printed by a simple serial printer, at a high readout rate, by detecting the position of a character to be recognized.

CONSTITUTION: Data S3 on the 1st column of a sensor is stored temporarily in a projection memory 51 as 1 for the black part of a character and as 0 for the white part, and data on the 2nd column is ORed with said data to store the result in a memory 51. On the completion of a scan on one character, the data in the projection memory has 1 only bits corresponding to the maximum height of the character. Then, the number of bits of the memory 51 is equalized to the number of bits of one column of the sensor to know which part of the visual field of the sensor the character is present at. A character center detecting circuit 53 counts the order of the bit in the memory. The 2nd character is the same, and the center values of all characters in a character train on the same row are found, and the mean value S54 is sent to and compared by a comparing circuit 54 with a fixed value S'53, thereby sending out an output S5 when S'53< S54. On the basis of the output S5, the position of the OCR sensor part is moved to above and below the character column.