A portable terminal apparatus includes a first body having a base, to which a first hinge arm is provided, the first hinge arm including a first axis hole having a protrusion extending axially; and a second body having a base, to which a second hinge arm including a second axis hole is provided. The apparatus also includes a hinge axis that includes an axially provided groove to be engaged with the protrusion, and that is fitted to the first axis hole and the second axis hole, so as to connect the first body and the second body, allowing opening and closing movements of the first body and the second body. The protrusion is formed such that an end of the protrusion facing the second hinge arm is positioned inside the first axis hole inwardly from an end of the first axis hole.