Abstract: The packaging box for bottles is made from a blank in a flexible foldable material that comprises two similar body panels which are foldable against each other about a lateral generatrix and that form together a side wall for said box when their remote side edges are secured together, so that said box can be shelved flat in a collapsed form. The blank further comprises two symetrical bottom elements having the shape of a half-section of the bottom face of said box, with two bottom flaps connected each along the diameter of one of said bottom elements. The two bottom flaps are securable flat on each other into a grip for pushing said bottom elements into said side wall where they are blocked by jamming, thereby erecting said box, that further constitutes a strengthening element for said bottom face of said box.