PURPOSE: To provide a powder treating device whose assembly and disassembly works are easy and whose manufacturing cost is low and which bears comparison with that having a circulating circuit.

CONSTITUTION: A powder treating device in which a rotating disc 104 circumferentially equipped with impact pins 105 is arranged in an impact chamber 109 and an impact ring 108 is arranged along the outermost circumferential track surface keeping a constant space to the track is provided. A circulating space for powder to be treated is further provided in front of the rotating disc 104 in the impact chamber 109. Let the width of the impact pin 105 in the direction of a rotating shaft 106 be (x) and the width of the impact chamber 109 formed between the side of the rotating disc 104 on the installed side of the impact pins 105 and the inner wall of the impact chamber 109 opposite to the side of the rotating disc 104 be (y), the circulating space is constituted so that the ratio x/y may be 0.2-0.8.