PURPOSE: To enable relearning exerting less adverse influence on other data without holding initial learning data at all times.

CONSTITUTION: When performing the relearning, a relearning part 12 first generates teacher signals (desirable output to input) taught as the output at the time of initial learning, adds them to an output element 5 and outputs the sample of an input vector (input sample) from an input element 1. Successively, the sets of the sum-set of the input sample outputted from the input element 1 and the newly learned data and the desirable output to them are relearned as relearning data by a parameter learning part 11.