We propose a methodology to automatically extract the requirements from the documents and check the traceability between them. The documents include not only the text file but also PDF or image files. We also suggest a method to visualize the result with maps, numbers, and graphs. By comparing the results with those of expert reviews, we show that it is necessary to use knowledge-based method in future instead of the word-based method for improving the reliability. The results give more values when they are applied in already existing documents than those of newly developed product.