Identification of double layered thin film elements by backscattered electron (BSE) contrast imaging by scanning electron microscope (SEM) was examined. A flat type sample was formed with an inner layer composed of five different element areas (Au, Ag, Ge, Cu and Fe) 50 nm thick and a thin gold outer layer 2, 5, or 10 nm thick on a silicon substrate. Dependence of BSE intensities of the sample on the acceleration voltage of incident electrons was measured from 3 to 30 kV, and the acceleration voltage sufficient to discriminate different elements shifted from 8.8 to 10.2 kV depending on the increase of the thickness of outer gold layer. Moreover, the dependence of the substrate shape was also evaluated using Ge/Au double layered spherical nano-shells. The contribution of the nano-shell diameter to the BSE intensity was tested using different sized nano-shells. The contribution was within 10% for 1.5 times difference of the diameter of nano-shells. Results between flat thin film and the nano-shell were compared and those differences were within 6% for 10 to 20 kV of acceleration voltage, which indicates that inner elements of double layered thin film objects can be identified using BSE observation of the SEM at appropriate acceleration voltage.