To provide an agitator which can efficiently carry out agitation and mixing while mixing proper fluids fed from the outside, efficiently carry out drying and sterilization of materials to be dried when the fluids are used as fluids for drying such as high temperature steam in an agitator, and which can enhance operation efficiency in drying and sterilization works.

In the agitator performing agitation by jetting predetermined fluids fed from the outside by an agitating means in a container 1 to the materials to be agitated, material to be treated, in the container 1, a fixed conduit pipe 3 arranged in a direction of a rotary shaft is installed in a cylindrical rotary shaft 5 in the agitating means, the conduit pipe having a plurality of jetting openings 3a through its surrounding, and jetting the fluid fed into the fixed conduit pipe 3 through the jetting openings 3a so as to jet them into the container through a communicating part formed in one part of the rotary shaft 5.