Novelty: a foldable pet transportation rucksack-bag is disclosed. Constitution: the safety zipper (5,6) assisting the pet’s positioning inside the rucksack in multiple modes and the complete deployment or folding of this last (12,13), the lateral air ducts 3, the safety clip 4 liable to adjust the pet’s neck to the opening or completely close this last, the reinforced back 8 having internal separated layers allowing the folding of the invention, the reinforced bottom 9 offering better support and comfort to the pet, the opening 10 allowing the free movement and interaction of the pet with the ambient space and the user, and two smaller openings allowing the front feet of the pet to pass through. Advantage: the invented foldable pet transportation rucksack is also portable; its design facilitates the entry of the pet therein, in multiple modes, and ensures the free interactive behavior of the pet with the environment and its carrier.