A vehicle body rear structure includes a lower cross member joined to the lower surface of a rear floor panel, and an upper cross member joined to the upper surface of the rear floor panel along the lower cross member. The lower cross member forms a closed section together with the rear floor panel, and is connected to front mounting portions on both sides. The upper cross member forms a closed section together with the rear floor panel. A rear flange of the lower cross member and a front flange of the upper cross member are joined to be overlaid via the rear floor panel.