To provide a former that efficiently forms nanometer-size highly pure standard particles having a monodisperse uniform structure and being in the state alleviated in contamination and damage from a material which can be selected from a wide variety of materials and to provide highly pure standard particles.

This former is constituted by using a particle formation chamber 101 that forms highly pure particles by exciting a semiconductor target with pulse laser beams 109 in a low-pressure rare gas atmosphere, thereby subjecting the target to an abrasion reaction for release and injection and condensing and growing the released and injected matter in air, a chamber 102 that classifies the highly pure particles, and a chamber 103 that collects the highly pure standard particles on a substrate.