Pontchâteau (; ) is a commune in the Loire-Atlantique department in western France.
Pontchâteau is located in the northwest of Loire-Atlantique, 19àkm southeast of La Roche-Bernard (Morbihan), 30àkm south of Redon (Ille-et-Vilaine), 25àkm east of Saint-Nazaire and 53àkm northwest of Nantes. The town is crossed by the Brivet.
Pontchâteau is located at a major crossroads, at the junction of the RN 165, the Nantes-Vannes-Brest expressway, and the D 773, the Saint-Nazaire-Redon road.
Pontchâteau also lies on the SavenayâÂÂLanderneau railway line, and is served by a station.