Apparatus for inspecting side-wall of bottle

An apparatus for inspecting the sidewall of a bottle, comprises an illuminating unit (10) for applying light to the sidewall of a bottle under rotating; a photoelectric conversion unit (14) for photoelectrically converting a light transmitted image of the sidewall applied with light by the illuminating unit into electric signals; a defect detecting unit (24) for detecting a defect point within the light transmitted image which has been photoelectrically converted by the photoelectric conversion unit, based on the brightness of at least two points on an inspection scan line; and a judge unit (28) for judging if the inspection scan line is a defective scan line based on the defect point detected by the defect detecting unit, judging if there is a defect on the sidewall of a bottle based on the state of continuation of defective scan lines. The apparatus for inspecting the sidewall of a bottle of this invention detects a defective point from the light transmitted image of the sidewall of a rotating bottle, and detects if there is a defect based on the state of continuation of defective scan lines detected by the defective point.