There is provided a device identifying method for identifying an electronic device including therein an actual operation circuit and a test circuit having a plurality of test elements provided therein, where the actual operation circuit operates during an actual operation of the electronic device and the test circuit operates during a test of the electronic device. The device identifying method includes measuring electrical characteristics of a plurality of test elements, storing identification information of an electronic device by storing the measured electrical characteristics of the respective test elements, obtaining identification information of a certain electronic device by measuring electrical characteristics of a plurality of test elements provided in the certain electronic device in order to identify the certain electronic device, comparing the identification information obtained in the identification information obtaining with the identification information stored in the identification information storing, and, when the obtained identification information matches the stored identification information, judging that the certain electronic device is the same as the electronic device associated with the stored identification information.