A fragrance diffusion device includes:two opposing walls between them defining a cavity which extends transversally as far as a peripheral wall provided with an opening for diffusing fragrance to outside the device,several openings formed in each wall and which pass through same so as to allow, in the case of a first wall, the fragrance to pass into the cavity from a first zone which is adjacent to the first wall and separated from the cavity by this wall and, in the case of the second wall, the fragrance to pass from the cavity to a second zone which is adjacent to the second wall and separated from the cavity by this second wall,a duct passing through each of the two walls and extending into the zone adjacent to the relevant wall so as to place each zone in communication with the cavity.