The invention broadly contemplates an apparatus that makes it possible to easily lift up and open a notebook type computer cover irrespective of a weight of the cover and stop the cover at a predetermined opened/closed position. A portable electronic apparatus includes: a main body provided with an input operating portion, a cover provided with a display unit, a hinge mechanism including a rotary shaft fixed to the cover and a support member fixed to the main body. The apparatus includes an electromagnetic mechanism having a permanent magnet and an electromagnet, in which the permanent magnet and the electromagnet are disposed with respect to the rotary shaft so that when the current is applied or not applied to the electromagnet, a repulsive or attractive force is generated which allows the rotary shaft to be in a rotatable state, and thereby allow an opening/closing torque to act on the cover.