For suppression of remarkable bending of a blade axis caused in preforming of the turbine blades with complicated shapes using incremental forging, an effective method is proposed in which metal flow during forging is controlled by varying inclination angles of tools to a billet axis. The effect of the inclination angle of tool and the specific twisting angle on the bending of the blade axis is mainly investigated by carrying out forming tests of plasticine blades with inclined flat tools. The bending of the blade axis is reduced with an increase in the specific twisting angle. The optimum inclination angle of tool, at which the bending of the blade axis is minimized, exists and depends on the specific twisting angle. The complexly curved surface of the blade can be roughly generated using the proposed method.