Provided is a method for producing a zinc oxide powder that exhibits an excellent antimicrobial performance even when blocked from light. This production method contains a step for adding 150-250 g of a hexagonal flake-shaped zinc oxide powder to 1 liter of an aqueous zinc nitrate solution having a concentration of 2-4 M (mol/L) and performing a hydrothermal treatment for 5-15 hours at 130°C-180°C, and a step for subjecting the basic zinc nitrate produced by this hydrothermal treatment to a heat treatment for 0.5-3 hours at a temperature of 550°C-700°C in air or an inert gas atmosphere. This heat treatment is preferably carried out at a temperature of 575°C-650°C, and the antimicrobial activity per unit mass can be increased by pulverizing the powder after the heat treatment.
