Partial nucleotide sequences (∼8000 bp) of the mitochondrial DNA of two cerithioidean gastropod species—Cerithidea djadjariensis and Batillaria cumingi—were determined. The order of mitochondrial genes (eight protein genes, two ribosomal RNA genes, and nine transfer RNA genes) was identical between these two species. and remarkably different from the previously reported order in other gastropods. The results indicate that the genome structure of the common ancestor of Cerithioidea and its sister group, Hypsogastropoda, is almost identical to that of the common ancestor of Gastropoda; moreover, independent mitochondrial genome rearrangements were identified between the lineages of Cerithioidea and Hypsogastropoda. The rearrangements within Cerithioidea can be explained by the inversion of a single tRNA gene, two translocations of a single tRNA gene, and three translocations of a genome fragment containing a tRNA gene and protein-coding gene(s).