Although extensive research on tsunami deposits has been conducted on the Pacific coast of Japan, such deposits on the Sea of Japan coast have received little attention. Consequently, little is known about tsunamis along this coastline, especially for events that occurred before the 19th century. The aim of the present study is to enhance this record based on tsunami deposits in Lake Kamo and Iwafune Lagoon in the Niigata area.Based on analysis of six borehole cores, twenty-four likely tsunami deposits that formed during the last approximately 9000 years were identified in Lake Kamo, and nine likely tsunami deposits that from between approximately 9000 and 2200 cal BP were identified in Iwafune Lagoon.The likely tsunami deposits of Lake Kamo and Iwafune Lagoon have revealed the first detailed tsunami history for the last approximately 9000 years in the northern Sea of Japan.