A liquid crystal display module, a liquid crystal display device, and a method for assembling the liquid crystal display device, which are capable of minimizing the overall size of the liquid crystal display device by improving an engaging structure between the liquid crystal display module and a case, are disclosed. Engaging holes are formed in an unused region of a top chassis, a mold frame and an end portion of a back cover. One side of a shaft screw is engaged with a catching member integrally formed with the inner side upper surface of a case. The other side of the shaft screw penetrates through the engaging holes of the top chassis, the mold frame, and the back cover and is engaged with a nut screw on a rear surface of the back cover. Accordingly, a separate space for installing a fixing member for fixing the mold frame and the back cover to the case is not needed, and the case, the mold frame, and the back cover is not engaged by using a separate screw. Therefore, the overall size of the liquid crystal display device can be minimized, and the number of parts and the number of assembling processes can be remarkably reduced.