An object of the present invention is to provide rounded zinc peroxide particles having a large particle diameter, the rounded zinc peroxide particles having excellent performance because they have an average particle diameter of 0.04 μm or more, a small aspect ratio and a shape close to a spherical shape； rounded zinc oxide particles which are obtained by calcinating the rounded zinc peroxide particles and which have a small aspect ratio and a sharp particle size distribution； a method for production thereof； and a cosmetic and a heat releasing filler each containing the rounded zinc oxide particles. Provided are rounded zinc peroxide particles having an average particle diameter of 0.04 μm or more and an aspect ratio of 2.0 or less, and rounded zinc oxide particles which are obtained by thermally decomposing the rounded zinc peroxide particles and which have an average particle diameter of 0.04 μm or more and an aspect ratio of 2.0 or less.
