A foldable display device includes a first casing having a first receiving cavity inside, a rewinding component disposed in the first receiving cavity, a second casing disposed on a side of the first casing, a stretching component slidably having an end slidingly connected to the first casing and another end rotationally connected to the second casing, and a flexible display component having a part disposed on a same side of the first casing and the second casing and another part protruding into the first receiving cavity and connected to the rewinding component.