Abstract: The inspection method, in order to detect and locate defects (5) included within the thickness of the transparent material (2) to be inspected, consists in uniformly illuminating a bright background (7) placed relative to the camera (4) behind the material (2) in order to be viewed by transparency through the material (2), covering the field of view of the camera (4) and serving as contrast reference, in laterally illuminating the surface of the material (2) in order to distinguish defects (5) included within the material (2) from parasitic elements (11) deposited on its surface, in viewing by transparency, by the camera (4), placed in the vertical to the surface of the material (2), a sequence of contrasted images reproducing the thickness of the material (2), and in processing information acquired by the successive images which are representative of the material (2) seen in its thickness in order to detect and locate the defects (5) included within the thickness of the material (2).