A portable terminal case and a method for controlling a smart key of a portable terminal are provided. The portable terminal case may include a cover unit for covering and protecting a rear side of a portable terminal and a coupling unit for connecting with a connector exposed on a rear side of the portable terminal. A seating surface for receiving a smart key may be formed in an inner side of the cover unit and the coupling unit may include a communication port for communicating with the portable terminal and a power port for receiving power, which are electrically connected to the smart key received in the seating surface.