A hinge apparatus and a portable terminal are provided including a pair of housings configured to open or close and one of the housings is positioned in parallel with a side of the other to rotate the portable terminal about 90.degree. according to user preference. Thus, the user can enjoy the horizontal view of a screen of a display device. Consequently, the user can conveniently watch the screen provided through a multimedia service. The hinge apparatus that rotates a housing such that the housing is positioned in parallel with a side of the other housing provides a driving force exerted in a direction that is the same as or opposite to a direction the housing rotates to implement a semi-automatic operation and provide user convenience.