Loading container/mobile box, of the type whose corresponding vertices present certain corners for its handling, positioning and securing and said container/mobile box has its side faces and roof open, having solely the two front walls, in such a way that said two front walls (2) and (3) of the loading container/mobile box (1) are rotary with respect to their lower part and are actuated by at least one cylinder for each of them, said front walls (2) and (3) acting as support, fitting, fastening and tightening elements for a canvas (4) which covers the roof, between the two fronts, and which is likewise arranged with respect to both sides.