The present invention discloses an apparatus of extracting text from document image with complex background, a method of extracting text from document image with complex background, computer program and storage medium thereof. The preferred method of extracting text from document image with complex background according to the present invention comprising the steps of: a first edge extracting step of extracting edges which have higher contrast than a first contrast threshold from said image; a searching step of searching connected edges from said extracted edges; a second edge extracting step of extracting edges which have higher contrast than a second contrast threshold in case that the pixels number of said searched connected edges is bigger than a predetermined size, wherein said second contrast threshold is higher than said first contrast threshold.