To provide a paste preparation apparatus capable of much increasing stirring and shear effects heretofore and allowing a formulation high in alkalinity, high in carrier starch ratio and low in water dilution ratio in the preparation of corrugated board starch paste by one tank.

A turbine agitating element (2) having a plurality of blade vanes (3) inclining to a turbine disk is used in a tank (1) and the edge or the edge and the side of the blade vanes are provided with a groove notched in the shape of a tooth profile or an angle. Further, by using blade vanes whose edges slightly incline to the rotational direction the turbine agitating element is fixed in parallel with the underside of the tank to an axis (5) rotatably supported by both sides of the tank and, at the same time, baffles (4) in the shape of a sector having symmetrically angled notches at the edge portion of the arc of the sector age vertically fixed to the sidewalls or the underside of the tank.