In order to contribute to the field of disaster science, various research in Japan currently focus on the clarification of the phenomenon called "disaster." Due to society's demand for disaster prevention and disaster mitigation, these researches are carried out through collaboration among researchers in science, engineering, humanities, social sciences, etc. These research outcomes are aimed at the following: verification of disaster cases of earthquakes and volcanic eruptions; clarification of the disaster occurrence mechanisms of earthquakes and volcanic eruptions; sophistication of information for disaster mitigation of earthquakes and volcanic eruptions; and development of researchers, engineers, and human resources involved in disaster prevention operations and disaster prevention responses. This article puts these research outcomes together from four points of view: 1) research on earthquakes and volcanic eruptions disaster cases, 2) clarification of disaster occurrence mechanisms of earthquakes and volcanic eruptions, 3) sophistication of information for disaster mitigation of earthquakes and volcanic eruptions, and 4) development of researchers, engineers, and human resources involved in disaster prevention operations and disaster prevention responses.