To easily predict the winning number of numeric selection type public lottery at a high efficiency of prize winning.

When a computer operator inputs the data of the past winning number into a memory of a computer, the computer displays a value of recommendation per each ranking, a change analysis graph 26 per each ranking of the lottery winning number, a lottery winning number appearance time graph 22 showing the number of appearance of the lottery winning number per each ranking, the recommendation zone data showing a range of the high probability, in which the lottery winning number appears, and the upper and the lower probability display data displaying the probability of raising and lowering of the lottery winning number of this time in comparison with the lottery winning number of the last time per each ranking on the basis of the input data so as to provide the reference data for prediction of the lottery winning number to the computer operator.