Chemical reactions are fundamental phenomena in nature. Much variety compounds have been generated by natural resources and synthesized artificially. Prediction of the reaction products from reactants and reaction condition is one of my research themes. This is one of the difficult problems in chemistry.Attempts to chart a course through the "universe of chemical reactions"Solving the chemical reaction prediction problem entails finding a solution from a huge number of possibilities of reactions that occur as a result of complicated interactions between several factors concerning structural and electronic properties of reactants, reagents, catalysts, and solvents, and conditions such as temperature, density, pressure, and reaction time. To find a solution, the space with broad diversity to be searched ought to be reduced. Hence, chemists must seek ways to reach the solution within an acceptable time by reducing the space in a rational way.Chemoinformatics is a new discipline that has a possibility to reduce the size of the search space by using chemical information as well as informatics technologies. Chemoinformatics is an interdisciplinary field that aims at solving chemical problems by applying informatics methods. We have been attempting to chart a course through the "universe of chemical reaction" by using the chemoinformatics approaches.