Add to ORKGA tsunami accompanying the Niigata Earthquake of June 16, 1964 is described on the basis of mareograms collected in the vicinity of the source area and a field survey, carriedout immediately after the earthquake by the members of the Earthquake Research Institute, along the coast of the Japan Sea from Akita to Naoetsu. The generating area of the tsunami, estimated by means of an inverse travel chart of the wave front based on the arrival time of the initial motion of the tsunami to the coastal station, is located in the sea on the continental shelf, extending about 90km in an elongated shape roughly parallel to the coast line from the northern part of Niigata Prefecture to Yamagata Prefecture