Chabahar Bay is located along the coast of the Oman sea in Sistan province in southeast of Iran. This area is a part of coastal Makran zone (one of the geological zones of Iran) that had undergone sea level changes along the Late Quaternary. Multiple sedimentary sequences and several paleoshorelines were formed due to these processes. In this investigation, 21 paleoshorelines were recognized by using GIS analysis. In the borehole at the north of Chabahar Bay, 14 layers were discovered that could be related to Late Quaternary sedimentary sequences and correlated to glacial and interglacial periods. All layers of borehole were analyzed for grain size, sedimentary structures and fossil contents. Four radiocarbon measurements have been made on the lowest and uppermost marine layers of borehole and on C7 and C21 of paleoshorelines. The lowest layer of borehole has 17,600 ¹⁴C yr B.P, related to Cataglacial or Flanderian transgression, outcropped at 15 m height and 5,300 m distance to present shoreline. Sedimentary sequences have shown 4 transgressions and retrogressions occurred from Cataglacial to the present. On the other hand, from 4,690K40 yr B.P, 20 paleoshorelines have been formed, which the duration of each may be about 230 years.