The Bras de Bronne (; sometimes spelled Bras de Brosne) is a small river in northern France whose course crosses the departement of the Pas-de-Calais. Its source is at the hamlet of Etreuille, near the village of Saint-Michel-sous-Bois. It flows through the communes of Humbert, Sempy, Aix-en-Issart, Marant, Marenla and joins the river Canche at Marles-sur-Canche.<br> In winter, it is fed by an even smaller river at the commune of Quilen.<br> There's an ancient watermill at Sempy.