[Problem] To provide an attachment that can provide a fixed distance between the tips of arms and a crossbar, a workpiece transfer device with the attachment capable of transferring an upstream side workpiece to a left position or right position on the downstream side while turning the workpiece, and a workpiece transfer method using the workpiece transfer device with the attachment. [Solution] The present invention provides an attachment 10 that is used in a double arm type workpiece transfer device, provided with a holding means 1 for picking up and holding a workpiece W, a crossbar 5 whereto the holding means 1 is attached, and a distance providing unit 7 attached to the crossbar 5, wherein the distance providing unit 7 is pivotally mounted on the tips of a pair of left and right arms of the workpiece transfer device and provides a fixed distance between the tips of the arms and the crossbar 5. The present invention also provides a workpiece transfer device X which is provided with the attachment 10, and a workpiece transfer method using the workpiece transfer device X with the attachment.