A foldable display device is provided, which includes a first body and a second body formed in the same plate shape and symmetrically arranged, a hinge device coupled to the first body and the second body to make the first body and the second body rotate in the range between an unfolded state in which the first body and the second body are put on the same plane and a folded state in which the first body and the second body overlap each other, and an angle maintenance device provided with first and second stopper units capable of fixing a rotating angle of the hinge device to a certain angle. Accordingly, the inclination angle of the display device can be freely adjusted to form an acute angle or an obtuse angle in addition to two folding and unfolding operations of the hinge device and the adjusted angle can be temporarily maintained to further improve convenience in use.