The Standard Model is extremely successful for describing the present-day physics of the elementary particles. However, there are several puzzles to be solved. I am very much interested recently in the puzzle of the Higgs particle, which is one of the crucial ingredients in the Standard Model. The Standard Model predicts the mass of the Higgs particle at about 100 GeV. However, bosons like the Higgs particle acquire huge masses from quantum corrections, in principle. It is, therefore, quite natural to consider that the Higgs particle receives a huge mass of the order of 1018 GeV on the the Planck scale. One may assume that the Higgs particle obtains a mass of about 100 GeV because of a miracle cancellation between a tree-level mass and the quantum corrections. But, that seems very unnatural and I do not believe it is the case. The above problem can be easily solved if there is supersymmetry, that is, an exchanging symmetry between a boson and a fermionOn the other hand we know that masses of a boson and of a fermion are the If the symmetry is .exact, same for each other. fermions do not receive large mass corrections from the quantum effects and hence masses of bosons are stable against the quantum corrections. Therefore, we may naturally explain the 100 GeV mass for the Higgs particle if the supersymmetry-breaking scale is about 1 TeV. We applied the above idea to the Standard Model and found an upper bound of the Higgs mass as <130 GeV. I expect that this prediction will not only be confirmed at the coming LHC experiment but also that various particles predicted in the supersymmetric Standard Model will be discovered at the LHC.