Elementary particle physics is currently understood based on the Standard Model, which is a gauge theory of three fundamental forces (strong, weak, and electromagnetic forces) with quarks and leptons as fundamental constitutes of matter. In this model, however, dynamics behind the mass generation mechanism of elementary particles is unknown. Furthermore, physics beyond the Standard Model is necessary to answer such questions as; whether the three forces are unified, what is the dark matter of our Universe, and how matter-dominated Universe arose in the history of our Universe. Various experiments at accelerators like the LHC (Large Hadron Collider) and those at cosmic fronts have been carried out to explore a new domain of particle physics. Researches in our particle phenomenology group include various aspects of theoretical studies on physics beyond the Standard Model, ranging from construction of a new model of elementary particles to proposals to test new physics models through on-going and future high-energy experiments and cosmic observations.