1. A method of inspecting a plurality of target portions on a substrate having components mounted thereon by using an image taken of said substrate by image taking means, said method comprising preparation steps and inspection steps, said preparation steps including: step A of obtaining a standard image that is obtainable when the field of vision of said image taking means matches a specified area on a substrate; step B of obtaining a positional relationship between said image taking means and said substrate that is necessary for position-matching said image taking means with said specified area; step C of setting an inspection area at a target portion on said standard image; and step D of registering by correlating said standard image, the positional relationship obtained in said step B between said image taking means and said substrate and the positional relationship set in said step C between said inspection area and said standard image; said inspection steps including: first step of creating a target image for inspection by position-matching said image taking means to a target substrate for inspection based on the positional relationship registered in said step D between said image taking means and said substrate; second step of matching said target image created in said first step with said standard image registered in said step D and thereby detecting displacement values of said target image with respect to said standard image; third step of correcting the positional relationship registered in said step D between said inspection area and said standard image by said displacement values detected in said second step and setting an inspection area on said target image based on said corrected positional relationship; and fourth step of carrying out an image processing for said inspection steps by using image data in said inspection area set in said third step.