We conducted a detailed bathymetric survey of a chain of seamounts named the Joban Seamount Chain (JSC). extending N53 degreesE over a distance of about 394 km on the ocean floor located east of the southern Japan trench. We surveyed a total of nine seamounts in the JSC and obtained their precise shapes and locations. Two of the seamounts. Hitachi and Futaba seamounts, were newly found and named. Two seamounts, Ryofu and Futaba. seem to lie in another line parallel to the JSC, which probably also includes Katori seamount. Two other seamounts, Iwaki and Hitachi seamounts, were classified as guyots and Iwaki has: a terrace on its northeastern side. Another isolated guyot, Daigo-Kashima, is located close to the southeast of Daiyon-Kashima seamount. The origin of the JSC remains uncertain owing to the lack of reliable ages, but formation at a congregation of hotspots or some combination with fissure eruption appear to be possible candidates. (C) 2001 Elsevier Science B.V. All rights reserved.