The heteroepitaxial growth of 3C-SiC films on Si(100) substrates by the hot-mesh chemical vapor deposition (HM-CVD) method using monomethylsilane as a source gas was investigated. From the results of X-ray diffraction spectra, 3C-SiC crystal was epitaxially grown on Si substrates at substrate temperatures above 750°C. The SiC/Si interface was observed by cross-sectional scanning electron microscopy, and was confirmed to be void-free and smooth. The density of hydrogen radicals supplied to the substrate surface during the growth was also estimated measuring the optical absorbance change of tungsten phosphate glass plates. From the dependence of the growth rate on substrate temperature, the mechanism of SiC film growth by HM-CVD was considered.