We, humans, can extract variety of knowledge from given data by the full use of our reasoning. However, such reasoning ability of humans is so limited that most of the massive and complex data acquired through computer network are wasted without any humans' inspection. To provide efficient remedies to this difficulty, our department studies novel reasoning approaches to extract knowledge from the massive and complex data by using computers. These techniques are named data mining and knowledge discovery. We also study the application of these techniques to variety of fields such as science, information network, quality/risk management, medicine, security, marketing and finance. Recently, we obtained significant outcomes in the research topics of knowledge discovery from extremely high dimensional data, knowledge discovery from graph structured data, data mining of comprehensive knowledge and discovery of time dependent law equations from data.