The stratigraphy of tsunami deposits along the Japan Sea, southwest Hokkaido, northern Japan, reveals tsunami recurrences in this particular area. Sandy tsunami deposits are preserved in small valley plains, whereas gravelly deposits of possible tsunami origin are identified in surficial soils covering a Holocene marine terrace and a slope talus. At least five horizons of tsunami events can be defined in the Okushiri Island, the youngest of which immediately overlies the Ko-d tephra layer (1640 AD) and was likely formed by the historical Oshima-Ohshima tsunami in 1741 AD. The four older tsunami deposits, dated using accelerator mass spectrometry 14 C, were formed at around the 12th century, 1.5-1.6, 2.4-2.6, and 2.8-3.1 ka, respectively. Tsunami sand beds of the 1741 AD and circa 12th century events are recognized in the Hiyama District of Hokkaido Island, but the older tsunami deposits are missing. The deposits of these two tsunamis are found together at the same sites and distributed in regions where wave heights of the 1993 tsunami (Hokkaido Nansei-oki earthquake, Mw = 7.7) were less than 3 m.Thus, the 12th century tsunami waves were possibly generated near the south of Okushiri