This article presents the author’s speculation on the desirable sustainable disaster mitigation for the era when the magnitude of natural disasters is getting greater. Nevertheless, disaster mitigation is not simple and still unclear because disaster mitigation is a preparedness against future problems and does not bring benefit immediately to people. It is difficult, therefore, for disaster mitigation project to be financially manageable under the current situations where many other issues, such as pandemics, environmental pollutions, support of higher educations, and many others require financial supports as well. Therefore, it is useful to combine the mitigation viewpoint with other points and make the disaster mitigation facilities be multi-purpose so that the overall income and expenditures may be in good balance. The use of inexpensive materials for which maintenance is easy is recommendable as well. Combination of public budgets with private funds is another good way so that disasters are mitigated by multiple barriers. This article picks up several examples of disaster mitigation in the past and today, and discusses their good points and lessons for future improvement.