Multiwalled carbon nanotubes (MWCNTs) were coated with a SiC layer using SiO vapor. The growth mechanism of SiC and the oxidation resistance of the SiC-coated MWCNTs were studied. The growth of the SiC layer was controlled by adjusting the partial pressure of CO, using carbon felt placed in a crucible. The nanometer-sized SiC particles were deposited onto the tubes by the reaction between SiO(g) and CO(g). On the other hand, the thin surface of the MWCNTs was converted to the SiC layer when the carbon felt was not used. The oxidation durability of MWCNTs was improved by the SiC coating. MWCNTs were oxidized completely in air at 650degreesC for 60 min. However, about 90 mass% of the SiC-coated MWCNTs remained after the same oxidation test.