The purple dye from shellfish, also variously known as Tyrian purple, purple of the Ancient, and Royal purple, was produced from the mucus of the hypobranchial gland of various species of marine mollusks. It is the oldest known pigment, the longest lasting, the subject of the first chemical industry, the most expensive and the best known since pre-Roman times in the Mediterranean region. In 1991, for the first time in Japan, shellfish purple was detected on fragments of ancient silk excavated from the Yoshinogari site, a village in Saga prefecture which dates to the Yayoi period (300 B.C.E.-A.D. 300). Since that time 1 have researched the dyeing properties and the history of shellfish purple, both in Japan and abroad. In this paper, the background to this study, the number of species that can be used for producing shellfish purple, the use of shellfish dye and archaeological evidence of shellfish purple are described.