1. An inspection apparatus of a disk-shaped substrate having film layers formed on its surface, which has an image capturing unit having a capturing view field including a predetermined surface at an outer circumference part of said disk-shaped substrate, successively capturing images of said predetermined surface in a circumferential direction of said disk-shaped substrate, and outputting image signals and an image processor processing the image signals successively output from said image capturing unit; said image processor having an image data generating means for generating captured image data expressing a captured image corresponding to said capturing view field extending corresponding to the circumferential direction of said disk-shaped substrate based on said image signals and a film layer edge position information generating means for using as a reference longitudinal direction positions showing positions in a direction traversing said circumferential direction at respective positions along said circumferential direction of a boundary line between a surface image part corresponding to said predetermined surface on said captured image and its outer image part so as to generate, from said captured image data, film layer edge position information expressing longitudinal direction positions at corresponding positions along said circumferential direction of edge lines of film layer image parts corresponding to said film layers on said surface image part, said film layer edge position information being able to be used to evaluate positions of formation of said film layers at said disk-shaped substrate.