1. An image analysis method comprising: an image acquiring step of acquiring, in time-series, images of frames comprising pixels in which pixel data of the respective images are acquired in time-series; an analysis area setting step of setting analysis areas to the images; a classification value calculating step of calculating a classification value of each of the analysis areas; a classifying step of classifying the images into one or more groups on the basis of the classification value; an average image calculating step of calculating an average image of the analysis area every group; a new image calculating step of subtracting the average image from each image of the analysis area every group to calculate a new image of the analysis area; and a calculation step of calculating a correlation value on the basis of the new images every group.