Shiroyama mounded tomb (kofun) No.1 is located in Asaminami ward, Hiroshima City. Up to now, several unearthed fragments of chest armor have been reported. While the details and chronological positions of those finds have remained unclear for a long time, an analysis of the fragments, which were kept in the Hiroshima Prefectural History and Folklore Museum, revealed that they belonged to a type of chest armor made of horizontally arranged long metal stripes riveted together (yokohagiita byōdome tankō). It became clear that they could be dated around the middle third of 5th century A. D.. Although there is still room for examination, all chest armor unearthed in the Hiroshima Bay area (including the materials from Shiroyama mounded tomb No.1) is basically considered to have been produced since the middle third of the 5th century A. D..