A mixing unit includes a mixing body having mixing elements that are stacked in a stacking direction and that extend in an extending direction in which the extending direction is perpendicular to the stacking direction. The mixing elements have a plurality of through holes to form a flow path therein, and are arranged such that part or all of the through holes in one of the mixing elements communicate with through holes in the adjacent mixing elements to allow fluid to be passed in the extending direction in which the mixing elements extend. The mixing unit may be employed in an agitation impeller or an adhesive dispensing unit.