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).

National Route 340 has a total length of 246.2 kilometers (153.0 mi).

National Route 340 was established by the Cabinet of Japan in 1975 between Rikuzentaka and Hachinohe.

[2] All junctions listed are at-grade intersections unless noted otherwise.