Abstract: A data analysis apparatus performs to acquire series data having character strings related to an information system to be analyzed as elements and series data having numerical values indicating a state of a device constituting the information system as elements, each of the series data having an index that enables comparison of element order relations within series and between series, classify the elements of each piece of the series data into classification classes, and output series data having classification values indicating classification classes as elements, integrate series data having classification values of the character strings as elements and series data having classification values of the numerical values as elements into one piece of series data, and detect an occurrence of a frequent pattern which is a combination of frequently occurring elements, using the one piece of series data obtained through integration.