PURPOSE: To mix without agitating a fluid material and in accordance with the viscosity of the fluid material by charging ≥2 kinds of fluid materials into a cylinder wherein balls are stacked.

CONSTITUTION: Fluid materials such as the base material of epoxy resin and a curing agent to be mixed are charged into a hopper 26 and a stop valve is opened. The fluid materials enter a cylindrical tube simultaneously, further enter a main body 1 wherein balls 6 are stacked through the small hole of a partition plate 3 and are branched into plural parts on the contact surface of the ball 6. The materials are brought into contact with many surfaces of the balls, fluidized and mixed. The rate of mixing can be regulated in accordance with the characteristics of the fluid material especially its viscosity by changing the diameter of the ball 6 and the height of the bed of the balls 6. Besides, when the viscosity of the fluid material is high, pressure is exerted on the fluid material in the cylindrical tube, for example, by supplying high- pressure air from an air passage 25.