Disclosed are a method of operating a selector device, a method of operating a nonvolatile memory apparatus to which the selector device is applied, an electronic circuit device including the selector device, and a nonvolatile memory apparatus. The method of operating the selector device controls access to a memory element, and includes providing the selector device including a switching layer and first and second electrodes disposed on both surfaces of the switching layer, which includes an insulator and a metal element, and applying a multi-step voltage pulse to the switching layer via the first and second electrodes to adjust a threshold voltage of the selector device, the multi-step voltage pulse including a threshold voltage control pulse and an operating voltage pulse. The operating voltage pulse has a magnitude for turning on the selector device, and the threshold voltage control pulse has a lower magnitude lower than the operating voltage pulse.