A hinge device of an information terminal, wherein the information terminal comprises a main body, a sub-body to be opened away from or closed to the main body while rotating about a hinge axis extending in one direction of the main body, and the hinge device for rotatably coupling the main body to the sub body. The hinge device comprises a driving part generating a driving force for rotating the sub body, and a clutch part for rotating the sub-body by the driving force of the driving part. When the sub-body rotates by external force, the clutch part prevents rotating force of the sub-body from being transmitted to the driving part. Such a hinge device configured as stated above allows the user to automatically open and close the sub-body of the information terminal by virtue of a driving motor provided therein, as well as to manually open and close it. Further, the user can freely adjust an opening angle of the sub-body to various angles, resulting in improvement in convenience of use. Furthermore, a clutch function provided in the hinge device prevents external force from affecting the driving motor.