Recently theoretical development of optical potential suggests a method to study the repulsive nature due to the three-body-force.Thus it is important to explore the repulsive nature of nucleus-nucleus interaction experimentally.The repulsive nature of the interaction can be observed as a change of diffraction pattern of the elastic scattering [1].We have finished the experiment of 100MeV/u 12C+12C to measure the angular distributions of elastic and inelastic scattering by using the magnetic spectrometer “Grand Raiden” at RCNP,Osaka University.We observed the angular distributions of ground states and three excited states.By comparing the theoretical results,we found the obvious three-body-force effect [1].Its also research the channel coupling effect of the cross section [2].