An arithmetic operation for calculating a value of a Masuda ratio (Mratio) or a value substantially equivalent to the Masuda ratio (Mratio) on the basis of the stock price information on a database is executed. The Masuda ratio (Mratio) is represented by a formula Mratio={(B-E)/SUM}.times.100, where SUM is a total number of stocks of a group of specific stocks forming a basis in generating one representative stock movement index, B is the number of stocks, average moving deviations of stock prices in a short term, an intermediate term, and a long term nearest to a reference time in one time unit selected from day, week, and month (MA1, MA2, and MA3) among the group of specific stocks having a magnitude relation MA1>MA2>MA3 indicating an upward trend when the number of stocks is B, and E is the number of stocks, MA1, MA2, and MA3 having a magnitude relation MA1