1. A sewing machine which is provided with a sewing machine bed on which a workpiece cloth is placed and a cloth feed mechanism provided in the bed to move the workpiece cloth in a predetermined feed direction, the sewing machine comprising: an imaging unit provided in the bed for imaging an underside of the workpiece cloth, the imaging unit including a first imaging unit which images a first range of the underside of the workpiece cloth and a second imaging unit which differs from the first imaging unit and images a second range of the underside of the workpiece cloth; an image synthesis unit which synthesizes the images obtained by the first and second imaging units, thereby obtaining a synthesized image; and a display unit which displays the synthesized image obtained by the image synthesis unit.