We have investigated the aluminum nitride microtubes made of aluminum nitride thin film. Aluminum nitride thin film deposited on aluminum foil forms microtubes of itself at room temperature when the aluminum foil is dissolved in hydrochloric acid solution. The aluminum nitride microtubes exhibit a large bending stress of 1100 94 megapascals. The bending stress is more than three times larger than the bending strength of aluminum nitride bulk. The diameter of the microtubes is proportional to the film thickness. The bending stress is independent of the film thickness and is fixed.