A part of an outer wall composing a clean box 2 becomes a component of a particle processing apparatus, a processing chamber 31 and the clean box 2 are integrated, the entire apparatus can be made compact, and in accordance with such compactness, even when a shaft sealing means 6 and an oil sealing means 323 are disposed in proximity to each other, reliable shaft sealing performance is secured, whereby a shaft sealing structure enabling processing of fine particles by high speed rotation is provided.Furthermore, integration of setting means for components accompanied with assembly and disassembly of the processing chamber is achieved, the entire assembling structure is simplified and the assembly work is made easier, whereby a particle processing apparatus the assembly and disassembly of which accompanied with cleaning work can be easily carried out in a short time without loss of productive efficiency.Moreover, use requiring a raw material supply unit 7 and use involving no necessity of a raw material supply unit 7 can be selectively achieved in a balanced manner in accordance with a supply manner for production in view of attachment and detachment accompanied with cleaning work, and this reduces the work burden of attachment, detachment, and cleaning of the supply unit 7 itself.