An air enclosure is provided. An air filling passageway for filling air into the first and second air cylinders is formed between two inner films. A plurality of first air cylinders and at least one second air cylinder are formed between two outer films. The second air cylinder includes an upper section, a middle section, and a lower section. The upper section, middle section, and lower section are isolated from each other. At least one tiny tube, connected with the upper and lower section is disposed at the middle section. The air is filled into the first air cylinders, as well as the upper section and the lower section, while the middle section remains flat. Because second air cylinder includes expanded upper section, lower section, and flat middle section, an accepting space with different shapes can be formed.