A backlight module includes a frame, at least one optical film and a flexible fixing-element. The frame includes a bottom plate and a sidewall connected to the bottom plate. The frame has an inner surface and an outer surface. The inner surface has an accommodation fillister. The frame further has a hole disposed between the accommodation fillister and the bottom plate and configured to connect the inner and outer surfaces to each other. The optical film(s) is disposed in the frame and includes a main body and a lug. The lug is inserted in the accommodation fillister and has a first opening. The flexible fixing-element has a first end and a second end. The flexible fixing-element is suitable to pass through the hole and the first opening. The first end of the flexible fixing-element is fixed on the outer surface. A display device adopting the backlight module is also provided.