1. A fuzzy controller formed on a one-chip semiconductor substrate, comprising: a fuzzy reasoner for outputting a control signal based on a reasoning rule and a membership function in response to an input signal; a rule storage for storing the reasoning rule and outputting thereof to the fuzzy reasoner, said rule storage comprising a non-volatile rewritable memory; a membership function storage for storing the membership function and outputting thereof to the fuzzy reasoner, said membership function storage comprising a non-volatile rewritable memory; and an extractor for extracting the reasoning rule and the membership function based on the input signal to the fuzzy reasoner and the control signal produced by the fuzzy reasoner, said reasoning rule and said membership function being transmitted to the rule storage and to the membership function storage, wherein contents of the rule storage and the membership function storage are overwritten when the reasoning rule and the membership function are transmitted thereto from the extractor.