Portable terminal device having a display unit utilizing a holographic screen

A portable terminal device, which employs a display unit utilizing a holographic screen, a main housing, a holographic screen, and an optical system. The holographic screen is disposed at a predetermined portion of the main housing while being exposed to an exterior of the main housing. The holographic screen optically displays information by means of image-light which is projected to the holographic screen. The optical system is spaced apart from the holographic screen and provides the holographic screen with the image-light.