A hinge assembly for pivotably connecting the display portion and the body portion of the portable computer comprises a first fastening portion for attaching to the display portion, a second fastening portion for attaching to the body portion, and a pivot portion for pivotably connecting the first fastening portion with the second fastening portion. The second fastening portion also has a first support arm for horizontally inserting into the insertion hole. The cables, for transmitting signals and power extending from the display portion, are electrically connected through connectors to the cable connection region. The cable connect region is formed on the rear wall or bottom wall of the body portion. The hinge assembly of the invention greatly reduces the extraordinary sound resulting from the rotation of the display portion. Also, some covering components can be eliminated to make the assembly much easier.