PURPOSE: To attain the automation of all processes and to improve both the processing speed and reading factor, by detecting a straight line based on the address information to decide the writing direction of the address information from the direction of the detected straight line and as a result eliminating the processes which are performed by the visual decision and operation of an operator.

CONSTITUTION: The address information is read optically out of a postal matter which has no limitation for the writing direction of the address information. In this case, a postal matter P is carried toward an arrow (a) on a carrying path 11, and the lengh of the matter P is detected by the 1st and 2nd detectors 13, 14 and a length detecting counter 16. The existable range of address information is decided by an arithmetic circuit 18, a comparator 17 which uses the output of the counter 16 for its input, etc. The range of address information is scanned optically for the matter P, and the address information is read at a reading part 12. This information is differentiated by a tip detection number defferentiating circuit 21 and then applied to an address underline detection FF circuit 22 to detect a straight line based on the address information. According to the direction of the detected straight line, the writing direction of the address information is decided. Thus all processes are automated to improve both the processing speed and the reading factor.