1. An area recognition apparatus comprising: scan reading means for reading image data by scanning an original document line by line in main-scan and sub-scan directions said image data image data including density data; a plurality of image processing devices for processing in parallel said image data from said scan reading means, each of said image processing devices corresponding to different respective areas on each line, scanned and each of said image processing devices includes mark portion detecting means for detecting a mark portion from said image data, and crossing portion detecting means for detecting a crossing portion where said mark portion crosses a predetermined portion on the original document in accordance with said image data; parallel-to-serial converting means for converting outputs of said image processing devices containing results detected by said mark portion detecting means and said crossing portion detecting means into serial data corresponding to the areas on each line; closed area recognizing means for recognizing a closed area formed by said mark portion and said crossing portion based on the serial data from said parallel-to-serial converting means and outputting serial data containing results of said recognition; and serial-to-parallel converting means for converting the serial data output from said closed area recognizing means to parallel data.