1. An inner defect inspection method for inspecting inner defects in an object on the basis of spatial discrete data which describe spatial shape and structure of the object by using spatial discrete elements, said inner defect inspection method comprising the steps of: extracting an inner defect from the spatial discrete data by using inner defect extraction means; collecting the elements included in a neighborhood range, which is set with a predetermined spread around the inner defect extracted by the inner defect extraction means, as related elements by using related element collection means; and measuring feature quantities such as a size and a position of center of gravity of the inner defect on the basis of the related elements collected by the related element collection means, by using feature quantity measurement means.