Molecular-dynamics calculations have been performed to examine behavior of carbon (C) atoms during crystal silicon (Si) growth from melted Si based on the ordinary Langevin equation employing the Tersoff empirical potential. From the analysis of the radial distribution functions, local coordination, and bond angle distributions, it was found that C atoms are four-fold coordinated in liquid Si and occupy the substitutional sites in crystalline Si grown from the melt. It has been also shown that aggregation of these substitutional C atoms induces defects such as five-and seven-member rings in crystalline Si.