PURPOSE: To directly correct the coupling weight of a network by maintaining the information of a weight list group, selecting a pair of lists from the group, performing the crossing of the list, and deciding the list that survives in the next generation.

CONSTITUTION: Each of weight list group storage means 101 stores several tens of weight lists in accordance with one perfect network. An adaptation evaluation means 102 calculates the output of the network represented by individual weight list, and stores an evaluation result as adaptation with the weight list. An evolution expediting means 105 selects the pair of lists with probability proportional to the adaptation, and generates a new list that is the result of crossing of those lists, and furthermore, varies the value of partial weight in probability fashion, and selects the list group with the same number of elements as that of a preceding generation from the group in which the new list group generated finally and an old list group are coupled, then, alternation of generation is completed. In such a way, such method can be applied to application in which no output of the network can be directly used.