The reverse resistance switching is observed in polycrystalline Nb2O5 film, which is one of promising candidates for nonvolatile resistance random access memory (ReRAM) devices. This reverse switching is compared with the usual behavior, in which the switching voltage V-LH from low resistance (LR) to high resistance (HR) states is lower than V-HL from HR to LR states. Based on these experiments, we propose a phenomenological mechanism for the resistance switching, which assumes the coexistence of LR and HR phases and the percolation transition. (C) 2009 Published by Elsevier B.V.