A backlight module is disclosed, which includes an outer frame having a sidewall and a hole formed on the sidewall, an inner frame disposed inside of the outer frame, and an adhesive device. The inner frame includes a block wall and a support. The block wall has an inner surface, an outer surface, and a breakable section. The outer surface is in contact with the sidewall, and the breakable section is disposed corresponding to the hole. The adhesive device is disposed on the support.