An apparatus for indicating machined surface flaws including material and machining flaws comprising first and second systems of optical instruments for detection of surface flaws separately, one of said systems comprising a source of light energy, a beam splitting prism splitting a portion of the light rays coming from said source of energy as a bundle to pass through in one direction, while deflecting a portion of said light in a second direction, the path of said one direction including a first lens, a deflecting mirror, and a second lens, said second lens being arranged confocally with said first lens, thereby permitting the light rays incident thereon to strike said surface to be tested in a parallel arrangement, said one of said systems further including an objective which transmits at least part of the amount of light reflected by said surface to be checked via said second lens onto said mirror to said first lens, and deflected from said beam splitting prism to a photosensitive element, said photosensitive element being in the form of a photodetector for detecting said material flaws, and the other of said systems having a plurality of fiberoptic elements whose one ends have been arranged on the circumference of a ring surrounding said second lens, their other ends being terminated in an annular member, confronted by a correspondingly shaped member, and which also carries further photosensitive elements in the form of photodetectors for the purpose of detecting machining flaws.