1. A tuning apparatus which tunes a membership function to perform a fuzzy inference using a singleton as the conclusion-membership function, said tuning apparatus comprising: a) an error calculation means for receiving an output result of fuzzy inference and an output expectation value, and for redetermining an error between the output result of fuzzy inference and the output expectation value with respect to an input value of fuzzy inference; b) a distance calculation means for receiving a height signal, and for calculating: 1) a total sum of heights of conclusion membership functions in a defuzzy calculation in said fuzzy inference, 2) a ratio of a height of each conclusion-membership function to said total sum, and 3) a distance in proportion to said ratio; c) an updating means, connected to said error calculation means to receive the error and to said distance calculation means to receive the distance, for tuning and updating the conclusion-membership function by shifting a position of said conclusion-membership function according to said distance calculated by said distance calculation means and the error determined by said error calculation means; and d) a control means to which said error calculation means, said distance calculation means and said updating means are connected, for controlling said error calculation means, said distance calculation means and said updating means.