Abstract: An inspection apparatus which automatically inspects a bottom border portion of a transparent glass vessel for a foreign article accurately is disclosed. Light is projected and received by way of first and second polarization filters through a rotating glass vessel to image the vessel obliquely from below by a solid state image pickup elements of a camera. Brightness values of outputs of the elements of the camera are compared with threshold values for binary digitization and determined as abnormality values when they are higher. The threshold values are varied and the abnormality values are corrected in accordance with the positions of the elements of the camera, and then presence or absence of a foreign article is determined from the corrected abnormality values or the sum of them.