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 the time-series; an analysis area setting step of setting analysis areas to the images; an image selecting step of selecting, from the images, the images of two or more frames to be used in analysis; and a calculation step of extracting data pairs each comprising two pixels in which acquisition time intervals are the same in the analysis area of each of the selected images, and performing product sum calculation of each of the data pairs for all of the selected images to calculate a correlation value.