A backlight module comprising an optical component, a frame and an elastic member is presented. The frame has a first sidewall and a second sidewall. An end of the first sidewall is connected to an end of the second sidewall to form a corner portion. The first sidewall and the second sidewall are located at different sides of the optical component. The first sidewall and the second sidewall include a first angle therebetween. The elastic member is configured to be disposed on the frame. The elastic member includes a flange portion, a first extension portion and a second extension portion. The flange portion is configured to be disposed on the corner portion. The first extension portion extends along a first direction away from the flange portion and has a first surface. The second extension portion extends along a second direction away from the flange portion and has a second surface. A second angle is included between the first extension portion and the second extension portion. Wherein before the elastic member is disposed on the frame, the second angle is greater than the first angle; when the elastic member is disposed on the frame, the flange portion engages with the corner portion, the first surface is against an inner surface of the first sidewall, and the second surface is against an inner surface of the second sidewall.