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, wherein the calculation step performs auto-correlating or cross-correlating calculation of a two-dimensional or three-dimensional observation area by use of the following Equation (1) or the following Equation (2): G sa ⁡ ( ξ , ψ ) = ∑ η = 1 n ⁢ ∑ I η ⁡ ( x , y ) * I η ⁡ ( x + ξ , y + ψ ) / M 11 ( ∑ η = 1 n ⁢ ( ∑ I η ⁡ ( x , y ) / M η ) / n ) 2 ( 1 ) where G sa is a space auto-correlation value of RICS, n is the number of the frames to be used in the calculation, η is a parameter to specify the frame (η=1, 2,. .. , n), Iη is the pixel data for η-th frame, x and y are spatial coordinates of a point of measurement, ξ and ψ are variations of the spatial coordinates from the point of measurement, M 11 is the number of data product sum calculation times, M η is the total number of the data of the η-th frame, and the number n of the frames to be used in the calculation is represented by an integer that is two or more and not more than the number of frames of acquired fluorescent images, G sc ⁡ ( ξ , ψ ) = ∑ η = 1 n ⁢ ∑ I 1 ⁢ η ⁡ ( x , y ) * I 2 ⁢ η ⁡ ( x + ξ , y + ψ ) / M 12 ( ∑ η = 1 n ⁢ ( ∑ I 1 ⁢ η ⁡ ( x , y ) / M 1 ⁢ η ) / n ) ⁢ ( ∑ η = 1 n ⁢ ( ∑ I 2 ⁢ η ⁡ ( x , y ) / M 2 ⁢ η ) / n ) ( 2 ) where G sc is a space cross-correlation value of the RICS n is the number of the frames to be used in the calculation, η is the parameter to specify the frame (η=1, 2,. .. , n), I 1η is fluorescence intensity data of the η-th frame of channel 1, I 2η is fluorescence intensity data of the η-th frame of channel 2, x and y are spatial coordinates of the point of measurement, ξ and ψ are variations of the spatial coordinates from the point of measurement, M 12 is the number of data product sum calculation times, M 1η is the total number of the data of the η-th frame of the channel 1, M 2η is the total number of the data of the η-th frame of the channel 2, and the number n of the frames to be used in the calculation is represented by an integer that is two or more and not more that the number of frames of acquired fluorescent images.