Backlight assembly and the display device using the same are disclosed. Backlight assembly comprises a container and a detector. The container holds a light and electromagnetic field generating source and a sampling portion for passing the light and/or electromagnetic field. The detector is located on the outer space of the container and has an electromagnetic field reactive sensing unit and a body to support the sensing unit. Therefore, the backlight of the present invention can protect lamp from the successive malfunctioning and prevent fire.