Method of inspecting a cap wrap-fitted to a neck of a bottle and apparatus therefor

A method of inspecting a wrap-fitted state of a cap (1) that is wrap-fitted to the neck of a bottle (20) by detecting a positional relationship between a bottle mark (P) and a cap mark (Q), wherein an optical lens (40) is arranged at a higher position on the vertical center axis of the bottle (20) to which the cap (1) is wrap-fitted, a single camera (50) is arranged at a higher position on the optical axis of the optical lens (40) to image the bottle mark (P) and the cap mark (Q) through the optical lens (40), an illumination device (60) is arranged for illuminating the bottle mark (P) and the cap mark (Q), the bottle mark (P) and the cap mark (Q) are simultaneously shot by the camera (50), and the obtained image is sent to an image processor to detect a positional relationship between the bottle mark (P) and the cap mark (Q).