Hadron interactions calculated by lattice QCD serve as the key pillar to establish the theoretical foundation of nuclear physics based on QCD. They are also essential inputs to determine the equation of state of dense matter, which is relevant to the structure of neutron stars and gravitational wave emissions / nucleosynthesis from neutron star mergers. In this talk, I will present the lattice QCD calculations of hadron interactions, in particular for baryon interactions such as nuclear forces and hyperon forces. I introduce our theoretical framework, the HAL QCD method, and discuss its advantage over the traditional method. I will then show the numerical results for baryon interactions obtained near the physical point, as well as the recent experimental confirmation of the lattice QCD predictions. Future prospects with the world's fastest supercomputer "Fugaku" will be also presented.