National Route 340 (国道340号, Kokudō Sanbyakuyonjūgō) is a national highway of Japan connecting the cities of Rikuzentakata, in southeastern Iwate Prefecture, and Hachinohe, in southeastern Aomori Prefecture. It travels south to north and has a total length of 246.2 kilometers (153.0 mi). It serves primarily as an alternate, inland route to National Route 45 through the northeastern part of the Tōhoku region.