Abstract: This invention relates to a work edge detection mechanism that enables an edge of a work to be viewed clearly through an aligning camera without adding an illumination device, and to a work transfer mechanism that uses the work edge detection mechanism. The work edge detection mechanism formed from a tubular body provided with an opening at one end thereof, the tubular body having a blocking member provided at the other end thereof, includes light-reflecting means on a lower surface side of the blocking member in order to reflect any light entering from the opening, is constructed so that the tubular body has an inside diameter (?1) at the opening of the tubular body and an inside diameter (?2) at a side of the blocking member, the inside diameter (?2) being greater than the inside diameter (?1), and enables vacuum suction transfer of the work.