Abstract: A surface flaw detecting apparatus of workpiece fast in flaw detecting speed, significantly shortened in the line cycle time, and simple and inexpensive in structure. By means of a control device, while a work rotating device is rotating a work about its axial line, a cleaning device remove soiling from the surface of the work, and its surface is illuminated by a lighting device, and its reflected light is detected by a line sensor camera, and presence or absence of flaw on the work surface is judged by a judging device from the result of detection. This series of measuring operation is done while the work makes a full revolution about its axial line, and hence as compared with other optical measurement, the measuring time may be shortened remarkably.