A mobile apparatus includes a main body, a display part, and a hinge device. The hinge device opens and closes the display part from the main body and allows the display part to rotate. The hinge device includes a sliding unit that slides with respect to the main body, and a rotary unit rotatably formed with the sliding unit to engage the display part. The hinge device requires less installation space so that the mobile apparatus may be more compact. Furthermore, there is no visible installation line of the hinge device so that the mobile apparatus may have a more refined design.