Hydrothermal synthesis technique could be carried out for growth of ZnO nanowires at relatively low process temperature, and it could be freely utilized with various substrates for fabrication process of functional electronic devices. However, it has also a demerit of relatively slow growth characteristics of the resulting ZnO nanowires. In this paper, an external DC bias of positive and negative 0.5 [V] was applied in the hydrothermal synthesis process for 2~8 [h] to prepare ZnO nanowires on a seed layer of AZO with high electrical conductivity. Growth characteristics of the synthesized ZnO nanowires were analyzed by FE-SEM. Material property of the grown ZnO nanowires was examined by PL analysis. The ZnO nanowires grown with positive bias revealed distinctively enhanced growth characteristics, and they showed a typical material property of ZnO.