Sewing workpiece is set on a holding frame in such a manner that a predetermined sewing reference line of the sewing workpiece forms an inclination of a given angle δ relative to a plane perpendicular to a rotation axis of the holding frame. Desired sewing pattern data are corrected in accordance with a predetermined correction function with the given angle δ as a variable. Sewing is performed onto the sewing workpiece by the holding frame being relatively rotated and linearly moved in accordance with the corrected sewing pattern data. Thus, a desired pattern corresponding to the sewing pattern data can be sewn onto the workpiece in generally parallel relation to the predetermined sewing reference line.