An apparatus for agitation mixing comprises a casing including a flow channel through which fluid passes, an agitation body consisting of a shaft installed in the casing and connected to a motor and an agitation blade mounted on the perimeter of the shaft, a powder inlet attached to the casing to feed a powder into the casing, a liquid inlet attached to the casing in the vicinity of the powder inlet to feed a liquid into the casing, a powder inlet duct connected to the powder inlet, and an introducer placed in the powder inlet duct and connected to a motor.