Digital textbooks have been expected for providing multimedia information that the print textbooks could not handle. The original digital textbook can be fabricated relatively easily by using Epub or DAISY. Print textbooks are, however, employed as textbooks in the most of lectures in universities. Therefore, it is considered necessary to convert the content of the print textbook to the digital textbook simply and in a short time. In this paper, the digital textbook using PDF files of the print textbook was suggested as one of simple and practical solution to provide an alternative textbook for the physically disabled university student who has difficulty handling the print textbook. Then usability of the suggested method was evaluated experimentally from the point of workload. Result of the experiment indicates that the digital textbook fabricated as the alternative one for the print textbook by the suggested method has a potential to reduce workload for the physically disabled university students. In addition, the digital textbook with larger LCD display needs less workload than the print textbook. Then, there are not so much difference in the workload between the print book which is smaller than the print textbook and the digital book made from the print book.