It has been nine years since the Higgs boson was discovered at LHC.
However, the essence of Higgs physics, i.e., the origin of the spontaneous breaking of electroweak symmetry, has not yet been clarified.
On the other hand, a new physics model beyond the Standard Model (SM) must exist, due to phenomena which cannot be explained in the SM
such as the baryon number asymmetry of the Universe.
In this talk, I will first give a brief review of the Higgs physics,
and then discuss the possibility that the determination of the structure of the Higgs sector
is a "key" to explore new physics beyond the SM by introducing recent my works.