A detachable atomizing device and a container thereof are provided. The container is detachably assembled to an atomizing assembly. The container includes a cup and a flexible film. The cup has an opening arranged at an end thereof, the flexible film covers the opening of the cup, and the flexible film has a tension region and an outer ring-shaped region that surrounds the tension region. The tension region has a plurality of atomizing holes having an average diameter within a range of 1 μm to 20 μm, and the outer ring-shaped region is attached to the cup. When the cup is assembled to the atomizing assembly, a tension value of the tension region of the flexible film is increased from an initial tension value to an atomizing tension value by being pressed from the atomizing assembly, and the atomizing holes of the tension region are configured to allow liquid to pass there-through and to be formed as aerosol mist having an average atomized particle diameter less than a predetermined value. Accordingly, the cup and the flexible film that often need to be replaced are isolated from the atomizing assembly, and an expensive vibrator is disposed in the atomizing assembly, so that the service life of the detachable atomizing device can be extended.