The angular distributions of differential cross sections of 12 C + 12 C elastic and inelastic scattering populating the ground and excited states in 12 C up to 15-MeV excitation energy are precisely measured for the first time at an incident energy of 100A MeV to study the effect of repulsive three-body forces. Using the high-resolution spectrometer Grand Raiden at the Research Center for Nuclear Physics (RCNP), Osaka University, we have obtained the differential cross sections for the ground state (0 • -7.5• . The results are compared with microscopic coupled channel (MCC) calculations. The potential between the colliding nuclei is determined by the double folding method with three different complex G-matrix interactions, the ESC, CEG07b and MPa interactions. The CEG07b and MPa interactions, which include repulsive three-body forces, describe the data well, whereas the ESC interaction, which does not include repulsive three-body forces, fails to reproduce the data. The results provide evidence of repulsive three-body forces in12 C, and demonstrate the possible sensitivity of elastic scattering to three-body forces.