1. An observation method comprising: acquiring a plurality of captured images of a same position on a sample; extracting one or more regions to be observed from among the plurality of captured images acquired in the acquiring a plurality of captured images; classifying the one or more regions to be observed extracted in the extracting one or more regions to be observed; and integrating the plurality of captured images and generating an integrated image by selecting an integration method from a plurality of predetermined integration methods based on a classification result of the classifying the one or more regions to be observed, wherein said selecting an integration method further comprises selecting one of a weighted sum processing with difference information integration method, a weighted sum processing without difference information integration method, and a weighted sum after brightness adjustment integration method to be performed, based on at least whether or not the one or more regions are present at an upper side of a pattern and a relative brightness of said pattern.