PROBLEM TO BE SOLVED: To provide a microparticle group having a small particle diameter, and small fluctuation of the particle diameter.SOLUTION: A microparticle group is composed of a number of microparticles, the particle diameter of the microparticle is in a range of 100-1,000 nm, the sphericity of the microparticle is 10 nm or less and the deviation coefficient of the microparticle's particle diameter is 10.0% or less.【課題】粒子径が小さく、かつ、粒子径のばらつきが小さい微粒子群を提供する。【解決手段】多数の微粒子からなる微粒子群であって、微粒子の粒子径が100nm以上1000nm以下の範囲にあり、かつ、真球度が10nm以下であり、微粒子の粒子径の偏差係数が10.0%以下である。【選択図】図1