The taxonomic status of the Japanese Wonder Shell, Thatcheria mirabilis is questionable, because it has been classified in the family of Thatcheriidae, Turridae or Conidae (Superfamily: Conoidea). Conoidea is a large and diverse superfamily with more than 10,000 species. Based on shell and radula characters, it is classified into three families, i.e. Conidae, Terebridae and Turridae. However, seven families have been proposed based on foregut structure, shell and radula morphology. In the present study, the molecular phylogeny of Conoidea and the taxonomic status of Thatcheria mirabilis were determined by mitochondria DNA 16S rDNA. The results show that Conoidea includes three clades, presuming Conidae, Terebridae and Turridae. The mean genetic distances within clades were 0.12, 0.10 and 0.10, respectively. And, the distances between clades were 0.14~0.17. Phylogenetic trees reveal that Terebridae and Turridae were within the same group or sister group, Terebridae was closer to Turridae than to Conidae. Although Thatcheria mirabilis and Bathytoma luhdorfi have turrid-form shells, their phylogenetic relationship was close to Conus which was in Conidae`s clade. Some other species, i.e. Oenopota sagamiana¡BPhymorhynchus buccinoides and Raphitoma linearis were also in Conidae`s clade which had been placed in Turridae. In general, the results are consistent with the cladistic classification by Taylor et al (1993), Rosenberg (1998) and Bouchet & Rocroi (2005), but differenrt from the classification by Powell (1966) and Kohn (1998) based on shell characters. Additionally, the hollow, harpoon-like teeth and venom apparatus in Conoidea might independently evolve in each family.