An agitation mixer 10 comprises a casing 12 through which a fluid passes, an agitator body 15 installed inside the casing 12 and connected to rotation means 92, a liquid inlet 22 for feeding a liquid into the casing 12, and a powder inlet 24 for feeding a powder into the casing 12. In the agitation mixer 10, the powder inlet 24 is attached to a powder feeding apparatus 55 in which a screw for transporting the powder is installed and connected to rotation-vibration means 53.