The present invention is to provide an engaging structure applicable to a display device and including a housing and an inflatable element, wherein the housing serves as a protective case of the display device and is formed with at least one assembly hole, and the inflatable element is formed with at least one connecting portion, such that, when the housing is assembled into an accommodating space of the inflatable element and the inflatable element is fully inflated, the connecting portion is engaged in the corresponding assembly hole. Thus, the portions of the inflatable element that correspond in position to the accommodating space are tightly pressed against the sides of the housing other than the side where a screen is installed at the display device. Since the inflatable element is lightweight and occupies a tiny space while in a deflated state, it will effectively reduce storage space and transportation costs.