A device for fixing panels for constructing a piece of furniture, a bookcase, or a cupboard, comprises a first element which engages with a first panel, a second element which engages with a second panel designed to be assembled essentially perpendicular to the first panel, and a third element which engages with each the first and second elements, and a pulling device for acting on the third element so that when the two panels are assembled, the first and second elements are pulled toward each other. The third element is a high-tensile wire.