In order to probe the differences of matter and charge radii of atomic nucleus in the proton-rich C isotopes, measurements of reaction cross sections (sigma(R)) for C9-11 on proton targets in the energy range from 50 to 120A MeV were performed at HIMAC facility, NIRS. Owing to the large di fferences between proton-proton and proton-neutron scattering cross sections at this intermediate energy region, sigma(R) data for atomic nuclei on proton targets are expected to have the sensitivity to the di fferences between proton and neutron distributions in the nucleus. Present preliminary data are compared with the Glauber calculation, which suggest the larger enhancements of proton distributions in C-9 and C-10 compared to C-11.