Sewing device and sewing method

A sewing method in which a sewing mechanism is employed to perform sewing along a predetermined sewing line on a workpiece-to-be-sewn in a state of the workpiece-to-be-sewn having been shaped in a predetermined shape, the sewing mechanism comprising:

• a sewing machine needle configured to, by moving in a reciprocating manner, penetrate through or withdraw from the workpiece-to-be-sown;
• a post bed that faces the sewing machine needle with the workpiece-to-be-sewn disposed therebetween;
• and a pressing mechanism configured to press the workpiece-to-be-sewn against the post bed from a side of the sewing machine needle,
• the sewing method comprising:
• a step of shaping the workpiece-to-be-sewn in the predetermined shape by the workpiece-to-be-sewn being seated on a plurality of seating portions disposed along the sewing line of the workpiece-to-be-sewn;
• a step of forming a retraction region where both surfaces of the workpiece-to-be-sewn have been set adrift, by retracting some of the seating portions;
• and
• a step of performing sewing with the both surfaces of the workpiece-to-be-sewn being pinched by the sewing mechanism, in the retraction region of the workpiece-to-be-sewn, wherein
• in the step of forming the retraction region, interference of the seating portions and the workpiece-to-be-sewn is avoided by sequentially moving the seating portions in a first retracting direction of separating from a first undercut portion of the workpiece-to-be-sewn and in a second retracting direction of separating from a second undercut portion of the workpiece-to-be-sewn.