The powder magazine of Poste-de-Traite-de-la-Métabetchouane is an outbuilding built between 1760 and 1788 located in Desbiens in Quebec (Canada). It is the only surviving building of the , a trading post established at the mouth of the Métabetchouane River on Lac Saint-Jean. It is located on the site of the Métabetchouane archaeological site.