The present disclosure is a backlight module including a light guide plate, a supporter, and a light source module. The light guide plate has a light incident side. The supporter has a bottom plate, a sidewall, and a top plate corresponding to the bottom plate. The bottom plate extends from a first end of the sidewall toward the light guide plate, and the top plate extends along a second end of the sidewall toward the light guide plate. The length of the sidewall is longer than the length of the top plate, such that the top plate corresponding to the sidewall forms at least one breach to expose the second end of the sidewall. The bottom plate, the top plate, and the sidewall together form an accommodating space, and the light incident side of the light guide plate is disposed between the top plate and the bottom plate. The light source module is disposed in the accommodating space and partially exposed through the at least one breach. The light source module has at least one light emitting unit and a printed circuit board. The light emitting unit is disposed on the printed circuit board, such that an emitting surface of the light emitting unit can face the light incident side of the light guide plate.