A backlight assembly includes at least one lamp generating light, a container having a receiving space, and a lamp fixing member disposed in the receiving space of the container. The lamp fixing member includes base arms disposed substantially parallel with each other, at least one lamp clip that grips the at least one lamp and is connected between the base arms, and at least one buffer formed in the respective base arms to allow variation in a length of the base arms due to changes in a size of the receiving space. An image display device includes a display panel for displaying images, and the backlight assembly to provide the light to the display panel. The image display device also includes a top chassis having another buffer allowing variation in a length of chassis sections.