The Oirase River (Oirase-gawa) is a river located in eastern Aomori prefecture, Japan. The Oirase River is the only river draining Lake Towada, a large caldera lake on the border of Aomori and Akita Prefectures. The river flows in a generally eastern direction, through the municipalities of Towada, Rokunohe, Oirase and Hachinohe before exiting into the Pacific Ocean. The upper reaches of the river form a scenic gorge with numerous rapids and waterfalls, and is one of the major tourist attractions of the Towada-Hachimantai National Park. The lower reaches of the river are used extensively for irrigation.