Spiders have the greatest number of individuals and species, and the widest distribution, of any predacious animals. As of December 31, 2012, a total of 43,678 spider species and subspecies belonging to 3898 genera and 112families have been reported worldwide. With respect to the three categories of species, genus, and family, distribution areas differ greatly: 90% of species are limited to a single realm, whereas 90% of families are found in at least two realms, with many distributed worldwide. Continental distributions also vary. Asia has the greatest number of spider species, with a smaller number in Europe and none in Antarctica. The greatest number of species is found in Palaearctic and Neotropical realms, the fewest in the Nearctic realm. In this study, we divided world land areas into 53 basic geographic units based on geographical conditions, ecological conditions, and distribution patterns of all known spiders. We then analyzed species and genus distributions using a similarity general formula (SGF) and multivariate similarity clustering analysis (MSCA). In the resulting genus-based tree, all basic geographic units are clustered into 8 groups and 17 subgroups at similarity levels of 0.22 and 0.32, respectively. The eight groups are designated as East Palaearctic, West Palaearctic, Oriental, Afrotropical, Australian, New Zealandian, Nearctic, and Neotropical kingdoms. The 17 subgroups, or subkingdoms, are distributed as follows: East Palaearctic kingdom (Siberian and East Asian subkingdoms), West Palaearctic kingdom (European and Central Asian subkingdoms), Oriental kingdom (Southeast Asian, New Guinea, and Pacific Ocean Islands subkingdoms), Afrotropical kingdom (West African, Southeast African, and Madagascar subkingdoms), Australian kingdom (East Australian and West Australian subkingdoms), New Zealandian kingdom (New Zealandian subkingdom), Nearctic kingdom (North American and Central American subkingdoms), and Neotropical kingdom (Amazon and Andes subkingdoms). Spider geographical divisions differ from those observed for mammals in several ways: 1) the Palaearctic realm is easily divided into eastern and western components; 2) there is a low similarity level between New Zealand and the Australian mainland, such that New Zealand can be considered to constitute its own kingdom; 3) New Guinea and Pacific Islands subkingdoms are more similar to the Oriental realm than to the Australian mainland, with no evident division between the two realms corresponding to Wallace's line; 4) Central America is more appropriately classified as belonging to the Nearctic realm; and 5) the Nearctic realm is more strongly related to the Neotropical realm than to the Palaearctic realm. The first and second observed differences can be explained by earth plate tectonics and differing evolutionary histories of spiders and mammals. The third and fifth geographical distributional patterns by which spiders differ from mammals are similar to those uncovered from biogeographical studies of plants and other groups. Analyses with additional examples are needed to elucidate the reason for the fourth difference. The application in this study of SGF and MSCA-techniques developed in recent years by the first author-represents the first reported quantitative analysis of typical point-forms and vast amounts of distribution information to successfully generate results that are statistically, geographically, ecologically, and biologically logical. This approach should be applicable to additional animal groups.