An information processing apparatus such as a tablet PC has a rectangular magnesium body. Molded resin components are attached to the body, and have respective functions and engaging portions for releasably securing the body to a docking unit. The information processing device can be used while it is held with a hand or while it is attached to the docking unit. Molded resin components can make sliding contact with the docking unit, but the magnesium body will not make sliding contact with the docking unit and, therefore, the weak points of the magnesium body can be overcome.