PURPOSE: To cut the noise image of a window or a label which occurs on the two dimensional pattern of an address detector and to prevent the erroneous detection of an address position.

CONSTITUTION: The voltage level of the window or label part and the voltage level of a paper surface part are obtained from a video signal, and the difference between these voltage levels are obtained in a level difference detection part 50. Whether the level difference is larger or smaller than a certain value is obtained in a window/label selection part 60, and the window/label position information from a window/label detection part 40 is selected. Thus, by obtaining the size of the level difference and selecting the window/label position information, the erroneous detection of the address description position of the mail can be prevented.