A structure for a piece of furniture, such as a retractable bed, includes a fixed part and a pivoting part, the latter having an essentially flat frame and being hinged to the fixed part between an essentially vertical raised position and an essentially horizontal lowered position. The pivoting part includes at least one guide which extends approximately at right angles to the frame and at least one leg mounted on this guide in such a way as to slide, with an actuating device connecting the leg to the fixed part to move the leg between an extended position when the pivoting part is in the lowered position in such a way that its free end is standing on the floor and a withdrawn position when the bed is in its raised position.