1. A visual inspection method comprising: taking a photograph of an illuminated inspection target sample from above to generate an original picture; converting said original picture obtained by said taking into a binary picture; labeling said binary picture obtained by said converting to generate a labeling picture; forming a circumscribing rectangle circumscribing an outer circumference of said labeling picture obtained by said labeling; inverting said labeling picture circumscribed by said circumscribing rectangle formed by said forming to generate a inversion picture; removing a picture in a region surrounded by said outer circumference of said labeling picture and said circumscribing rectangle from said inversion picture obtained by said inverting to generate a removal picture; adding said removal picture obtained by said removing to said labeling picture to generate an inspection picture; and judging a pass or rejection of said inspection target sample based on said inspection picture obtained by said adding.