The Division of Condensed Matter Theory is actively engaged in theoretical research on the cutting-edge topics in condensed matter physics. Theoretical studies play a crucial role in condensed matter physics: those studies at various levels extract new discoveries from experimental results, and novel theoretical predictions also start as well as boost experimental works. For achieving a breakthrough in the condensed matter physics, the research based on novel ideas is essential and indispensable, in addition to continuous research for increasing the predictive power based on existing theories. This division now consists of three groups and six other groups of concurrent members. Together with other theoretical groups, the activity of this division covers various theoretical studies from basic theory based on analytical methods to large-scale state-of-art numerical computation using supercomputers, and actively develops the theory for forefront research subjects in the condensed matter physics. Discussions and collaborations are also actively pursued with experimental groups inside and outside ISSP.