Reaction cross sections for 15;16C on nuclear targets (Be, C, Al) and proton target are systematically measured in the intermediate energy range. Nucleon density distributions of 15;16C were deduced from the analyses of present data with existing experimental data using the Glauber-type calculation. Proton and neutron density distributions were also deduced separately from proton target data. Results of root-mean-square radii show a good agreement with theoretical calculations for both isotopes.