One of my research interests is hadron physics. Hadrons are particles that compose an atomic nucleus, such as protons, nucleons, and mesons. It is natural for me to be interested in hadron physics because most of the matter around us, and we ourselves, are hadrons. Particle theorists have known for several decades that the hadron physics is ruled by a fundamental theory called QCD. Many properties of hadrons, however, have not been derived from the fundamental theory yet. This is the problem which should be solved. I expect that essence of hadron physics may be understood by means of the holographic principle. My result based on the idea is in agreement with the experimental data of scattering processes of the hadrons.