Stable field emission is realized from well-separated tetrapod-like ZnO nanostructures with high purity. The ZnO nanostructures are painted on a highly doped silicon substrate covered by a Au layer with a thickness of 300nm. An emission current density of 18mA∕cm2 is obtained and degradation was not observed over a three day period. The fluctuations of the emission current are less than 2%. These experimental results indicate that tetrapod-like ZnO nanostructures are promising materials as cold cathodes for mass production.