Neutron is a chargeless massive particle with the lifetime in the macroscopic range, which is suitable for precision measurement of the small influence of new physics. We have started the experimental studies to search unknown interactions with slow neutrons. Combination of the pulsed neutrons provided by J-PARC and the advanced optical devices enables us to perform new types of high precision measurements. The unknown source of large CP violation should exist to explain the matter universe. One of the strongest constraint of the search for the large CP-violation is the result of neutron electric dipole moment. We are now discussing another approach to search neutron EDM by using dynamical diffraction of neutron wave with non-centrosymmetric crystals. The enhancement of the violation of time-reversal symmetry is predicted in the neutron capture reaction for some nuclei. We have also started the feasibility to search the T-violation with the neutron resonance capture reaction at J-PARC. Non-Newtonian effect of the gravity at the short range is lead by the existence of extra-dimension of the space. Neutron scattering with noble gas target enables us to measure the interaction at the range of the order of 1 nm. On the other hand, we are now planning the unknown force search lead by dark energy, like chameleon field, by using the interferometer.