In this work, the results of detailed investigations of classical current–voltage characteristics measured both on the macro- and nanoscale with the use of LC-AFM microscopy are presented. With decreasing frequencies abnormal hysteresis I(V) loops in a PbZrO3 single crystal were observed, showing a bipolar resistive switching behavior. The observed phenomena have been accounted for by the nonstoichiometry and defects produced electrochemically in the surface layers. Due to the nonstoichiometric composition of the crystal surface we showed the possibility of reversible transformation from an insulating to a conducting state in an antiferroelectric crystal by an electroforming process. The model of filamentary structure produced by extended defects and an electrochemical process is applied here to explain the data.