A manufacture method for a ZnO based semiconductor device includes the steps of: (a) preparing a ZnO based semiconductor wafer including a ZnO based semiconductor substrate having a wurzeit structure with a +C plane on one surface and a −C plane on an opposite surface, a first ZnO based semiconductor layer having a first conductivity type epitaxially grown above the +C plane of the ZnO based semiconductor substrate, and a second ZnO based semiconductor layer having a second conductivity type opposite to the first conductivity type epitaxially grown above the first semiconductor layer; and (b) wet-etching the ZnO based semiconductor wafer with acid etching liquid to etch the −C plane of the ZnO based semiconductor substrate