A correlation operation method includes: first processing executed to match a signal level of an AC component contained in a first signal data string made up with a plurality of sets of first signal data with a signal level of an AC component contained in a second signal data string made up with a plurality of sets of second signal data; and correlation degree calculation processing executed to calculate a correlation degree indicating a degree of correlation between the first signal data string and the second signal data string having undergone the first processing.
