1. A method of using image taking means for inspecting a plurality of target portions on a substrate larger than the field of vision of said image taking means and having components mounted thereon by using images taken of said substrate a plural number of times by said image taking means, said method comprising inspection steps for an inspection and preparation steps carried out prior to said inspection steps, said inspection steps and preparation steps are performed using a computer, said preparation steps including: step A of setting a plurality of target areas according to the field of vision of said image taking means on a standard substrate of a standard substrate considered to be of acceptable quality such that mutually adjacent ones of said target areas have an overlapping portion by a specified amount and taking individual images of said target areas; step B of creating a whole image of said standard substrate by combining the images obtained in said step A; step C of specifying the image in each area in said whole image created in said step B as standard image in corresponding target areas at a time of the inspection; step D of specifying position and size of inspection area suitable to the standard image specified in said step C based on substrate design data corresponding to said standard substrate and setting the specified data as set data of said inspection area; and step E of registering said standard image specified in said step C and the set data of the inspection area specified in said step D for each the target areas at the time of said inspection; said inspection steps including: first step of creating an object image for processing by matching the field of vision of said image taking means with one of said target areas; second step of comparing said object image for processing created in said first step with said standard image registered in said step E and thereby detecting a difference between said object image for processing and said standard image; third step of correcting set position of the inspection area based on the set data of the inspection area registered in said step E according to the difference detected in said second step and setting said inspection area at the corrected set position on the object image for processing; and fourth step of carrying out image processing for said inspection by using image data in said inspection area set in said third step; said first step, said second step, said third step and said fourth step being carried out for each of said target areas.