An exemplary backlight module includes a light guide plate (14), a frame (15), and an illuminator (16). The light guide plate includes a light incident surface (142), and a side surface (149) opposite to the light incident surface. The illuminator is adjacent the light incident surface. The frame receives the light guide plate and the illuminator, and includes an elastic member (156) either elastically pushing the side surface toward the illuminator or elastically pushing the illuminator toward the light incident surface.