A glass bottle inspection device comprising: rotating means that causes a glass bottle to rotate about a bottle axis; illuminating means that emits light toward a bottle mouth portion of the glass bottle; image taking means that takes an image of the bottle mouth portion illuminated by the light emitted from the illuminating means; and image processing means that detects sealing surface waving in a mouth portion image taken by the image taking means, wherein an optical axis of the image taking means is inclined upward relative to a horizontal line, wherein the image processing means is configured to: detect intersections A (Ax,Ay) and B (Bx,By), at which vertical lines a and b set further to the inside than left and right ends of the bottle mouth portion intersect a sealing surface of the bottle mouth portion in the mouth portion image taken by the image taking means, obtain a line segment c, which connects A and B to each other, set, in the mouth portion image, a vertical line d that passes through a midpoint C ((Ax+Bx)/2, (Ay+By)/2) of the line segment c, and obtain an intersection D, at which the vertical line d and the sealing surface of the bottle mouth portion intersect each other, and calculate a difference T between the intersection D and the midpoint C, and determine whether or not the glass bottle is good in accordance with a value of T. rotating means that causes a glass bottle to rotate about a bottle axis; illuminating means that emits light toward a bottle mouth portion of the glass bottle; image taking means that takes an image of the bottle mouth portion illuminated by the light emitted from the illuminating means; and image processing means that detects sealing surface waving in a mouth portion image taken by the image taking means, wherein an optical axis of the image taking means is inclined upward relative to a horizontal line, wherein the image processing means is configured to: detect intersections A (Ax,Ay) and B (Bx,By), at which vertical lines a and b set further to the inside than left and right ends of the bottle mouth portion intersect a sealing surface of the bottle mouth portion in the mouth portion image taken by the image taking means, obtain a line segment c, which connects A and B to each other, set, in the mouth portion image, a vertical line d that passes through a midpoint C ((Ax+Bx)/2, (Ay+By)/2) of the line segment c, and obtain an intersection D, at which the vertical line d and the sealing surface of the bottle mouth portion intersect each other, and calculate a difference T between the intersection D and the midpoint C, and determine whether or not the glass bottle is good in accordance with a value of T. detect intersections A (Ax,Ay) and B (Bx,By), at which vertical lines a and b set further to the inside than left and right ends of the bottle mouth portion intersect a sealing surface of the bottle mouth portion in the mouth portion image taken by the image taking means, obtain a line segment c, which connects A and B to each other, set, in the mouth portion image, a vertical line d that passes through a midpoint C ((Ax+Bx)/2, (Ay+By)/2) of the line segment c, and obtain an intersection D, at which the vertical line d and the sealing surface of the bottle mouth portion intersect each other, and calculate a difference T between the intersection D and the midpoint C, and determine whether or not the glass bottle is good in accordance with a value of T.