An exemplary backlight module (20) includes a light guide plate (250) including a light incident surface (251), a frame (280) accommodating the light guide plate and including a side wall (281), light emitting units (270) adjacent to the light incident surface of the light guide plate, and elastic members (240). The elastic members are detachably engaged with the side wall of the frame. Each elastic member is configured to elastically urge a corresponding light emitting unit such that the light emitting unit abuts the light incident surface of the light guide plate. In other examples, each elastic member elastically urges the side wall of the frame, or elastically urges the light guide plate. A liquid crystal display device using the backlight module is also provided.