Web-based education has been popularized in school, company training, and life-long learning. In this context, Web educational material with high reusability should be created. We think that the reusability of Web educational material consists of reliability and consistency of its content, and we focus on how to heighten this reusability. Our proposal is competitive information sharing approach, which allows authors to not only create and share the content of Web educational material, but also modify the content without other authors' approval. This approach aims at facilitating content refinement by giving the authors a trigger for discussion about the modified content. As content refinement is repeated in this way, the content reliability is heightened. On the other hand, the consistency is heightened by means of the functions that promote unification of terminology (wording) and semantic attributes. Based on this approach, we have developed the prototype of a Web-based collaborative authoring system.