A portable display device comprises: a first panel emitting light in a first direction; a second panel emitting light in a second direction; a substrate disposed between the first panel and the second panel; a first power supply unit applying a power supply voltage to the first panel; a second power supply unit applying a power supply voltage to the second panel; a switch control unit selectively controlling the first power supply unit and the second power supply unit; a first positive power supply voltage unit electrically coupled to the first power supply unit and applying a positive power supply voltage to the first panel; a second positive power supply voltage unit electrically connected to the second power supply unit and applying a positive power supply voltage to the second panel; a first negative power supply voltage unit electrically coupled to the first power supply unit and applying a negative power supply voltage to the first panel; and a second negative power supply voltage unit electrically connected to the second power supply unit and applying a negative power supply voltage to the second panel.