To provide a displacement detecting apparatus capable of detecting easily the displacement of a workpiece with a simple structure without lowering the throughput by providing an edge detecting means in some arm parts connected in series to each other.

A plurality of arm parts are connected in series rotatably and this displacement detecting apparatus for the workpiece is provided in a conveying mechanism for conveying the workpiece by retaining the workpiece with a most distal arm part. This displacement detecting apparatus is constituted to comprise: an edge detecting means for detecting an edge of the workpiece retained at least with the most distal arm part which are provided in arm parts other than the most distal arm part among the plurality of arm parts; and a displacement detecting part for measuring the displacement of the workpiece based on the detected value by the edge detecting means. Thus, with a simple structure, the displacement of the workpiece can be easily detected without lowering the throughput.