The growth of single-walled carbon nanotubes (SWCNTs) was examined by hot-filament chemical vapor deposition (CVD) at low temperatures using a double-layer film consisting of nickel and cobalt layers as a catalyst. Ethanol was used as the carbon source. At a growth temperature of 350°C, few SWCNTs were grown when a cobalt film was used as a catalyst, whereas the growth of SWCNTs was confirmed when a double-layer film consisting of nickel and cobalt layers was used as a catalyst. However, at a growth temperature of 450°C, the yield of SWCNTs was higher when the cobalt film was used than when the double-layer film was used. The optimum thicknesses of the nickel and cobalt layers for obtaining SWCNTs were 1.0 and 1.2 nm, respectively. By laminating the nickel and cobalt layers, the catalyst film changed into particles at a growth temperature of 350°C. To obtain such nanoparticles, a nickel layer should be formed on an oxidized cobalt layer.