Route 340 is a 30-kilometre (19 mi) long, mainly east/west secondary highway in the north-eastern portion of New Brunswick, Canada.

The route's western terminus is in the community of Janeville.

The road travels south-east to the community of Canobie.

Passing the community, the highway takes a 90 degree turn south passing the community of Canobie South.

The highway takes a 45 degree turn and travels to the community of Rocheville before taking another turn south then another turn east going towards Notre-Dame-des-Erables, Haut-Paquetville, and eventually Hautes-Terres.