Memristive switching, which is nonvolatile resistive switching in metal/oxide/metal sandwich structures, have attracted considerable attention not only for the next-generation nonvolatile memory but also for the artificial neural network computing. Despite the excellent memory performance, the physical origin of memristive switching occurring in the simple two terminal device structure had been missing, which was a central issue of this research field. It was widely accepted that the memristive switching is governed by formation and rupture of nanoscale conducting path in insulative matrix, however, extracting and evaluating such nanoscale conduction paths was difficult due to the lack of evaluation method. In this study, we demonstrate a unique approach to reveal the nature of memristive switching by using an oxide nanowire. The oxide nanowire successfully extracted the nanoscale conduction path and revealed the redox based conduction mechanism with the direct experimental evidence, which had been unfeasible in conventional thin film device form. The obtained results captured the many intrinsic features of memristive switching.