PURPOSE: To obtain a particulate state by crossing a first groove and a second groove and breaking powdery grain lumps by both impact colliding against the corner of the groove and impact wherein water flow becomes turbulent flow by two grooves when the powdery grain lumps are passed between a shaft and a case by water pressure.

CONSTITUTION: Powdery grain lumps are formed by immersing hard soluble powder in liquid and broken. In this case, a device is equipped with a shaft 12 wherein a first groove 18 is formed on the circumferential face thereof, a case 11 described below and a means 15 for intruding the liquid incorporating the powdery grain lumps between the shaft 12 and this case 11. The case 11 covers the shaft 12 while keeping a gap for the circumferential face of the shaft 12. A second groove 19 is formed on its inner circumferential face opposite to the shaft 12. The first groove 18 and the second groove 19 are formed so as to cross with each other. As a result, the powdery grain lumps are surely broken by both impact due to the corners of the grooves and impact wherein water flow becomes turbulent flow by the two grooves. Thereby the powdery grain lumps become a particulate state.