Disclosed herein are an apparatus and method for testing open and short circuits of conductive lines. A probe is brought into contact with one end of each of the conductive lines, AC power is applied, and the conductive lines are tested using electrical variations measured in the probe. By using a single-side probe device, it is possible to remarkably reduce the number of probes when the open or short circuit of a PCB pattern, a data transmission line or an electrical cable is tested and to remarkably reduce time or labor necessary for testing the open or short circuit. Since the measurement is performed only at one end of the conductive line to test the open or short circuit of the conductive line, it is possible to self-diagnose the open or short circuit when a single-side probe device is mounted in an input/output port of an electrical device.