  Effects of the center-of-mass correction together with the nucleon
electromagnetic form factors on the nuclear charge radius are systematically
studied with a relativistic Hartree-Bogoliubov model. Both one- and two-body
parts of the CM correction are taken into account. It is found that the one-
and two-body CM corrections, and the spin-orbit effect originating from the
nucleon anomalous magnetic moments are all of the same order in magnitude, and
that they give sizable impacts on the charge radius from light to heavy nuclei.
