It is an object of the present disclosure to provide zinc oxide powders having an average particle diameter of 1.1 µm or more and having an antibacterial property, an antibacterial agent comprising the same, and an antibacterial composition containing the same. Surface treated zinc oxide powders which have an average particle diameter of 1.1 µm or more, and which are surface treated by using at least one compound selected from the group consisting of silicon oxide, silicone oil, organic silicon compounds, and organic titanium compounds.
