The 15,338-bp long complete mitochondrial genome (mitogenome) of the Japanese oak silkmoth, Antheraeayamamai (Lepidoptera: Saturniidae) was determined. This genome has a gene arrangement identical to those of all other sequenced lepidopteran insects, but differs from the most common type, as the result of the movement of tRNAMet to a position 5’-upstream of tRNAIle. No typical start codon of the A. yamamai COI gene is available. Instead, a tetranucleotide, TTAG, which is found at the beginning context of all sequenced lepidopteran insects was tentatively designated as the start codon for A. yamamai COI gene. Three of the 13 protein-coding genes (PCGs) harbor the incomplete termination codon, T or TA. All tRNAs formed stable stem-and-loop structures, with the exception of tRNASer(AGN), the DHU arm of which formed a simple loop as has been observed in many other metazoan mt tRNASer(AGN). The 334-bp long A+T-rich region is noteworthy in that it harbors tRNA-likestructures, as has also been seen in the A+T-rich regions of other insect mitogenomes. Phylogenetic analyses of the available species of Bombycoidea, Pyraloidea, and Tortricidea bolstered the current morphology-based hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As has been previously suggested, Bombycidae (Bombyxmori and B.mandarina) and Saturniidae (A.yamamai and Caligula boisduvalii) formed a reciprocal monophyletic group.