1. A digital fuzzy inference apparatus comprising: latch means for latching a plurality of input signals simultaneously and holding said input signals over one inference period; a set of fuzzy rule operation means for performing operations of fuzzy rules constituted by membership functions; parameter storage means for storing parameters as a plurality of sets of parameters used for defining the membership functions of said fuzzy rule operation means; operation control means for causing each of the plurality of parameters stored in said parameter storage means to be supplied sequentially to said fuzzy rule operation means during a period when the input signal is latched in said latch means, and causing said set of fuzzy rule operation means to time-divisionally perform a fuzzy rule operation on the basis of said parameters; center-of-gravity calculating means for, when necessary fuzzy rule operations are completed on the basis of the plurality of sets of parameters, obtaining a center of gravity of an operation result which is output with respect to each rule of the fuzzy rule operation means; and repeat control means for causing said latch means to latch a plurality of input signals after said one inference period, and for repeating said fuzzy inference operation.