Electronic transport behavior of a ZnO inter-nanowire junction transistor was studied with atomic force microscopy (AFM) and scanning gate microscopy. Source-drain currents exhibit strong dependences on gate voltage, applied by a movable local gate. Noticeable local gating was observed when the tip is above the junction area of the inter-nanowire device, demonstrating that active region in the device is confined. Transport mechanism in the device was understood in terms of band bending by electronic doping. Our device structure is analogous to that of two ZnO grains separated by an insulating layer in polycrystalline varistor devices. (C) 2009 Elsevier Ltd. All rights reserved.