1. A speech recognition apparatus comprising: (a) a speech analysis portion for extracting parameters necessary for determining of spoken words; (b) a speech period detecting portion for extracting one or more combinations of speech periods using said parameters; and (c) a structure analysis portion responsive to said speech analysis portion and said speech period detecting portion for detecting feature points indicative of phoneme structure of each word using said parameters found within said detected speech periods and for determining a word through computation of similarity to predetermined proposed words in accordance with the presence and absence of the feature points, said structure analysis portion comprising: (i) an analysis procedure portion for indicating the procedure of automatically detecting feature points representative of phoneme structure for each word; (ii) an addition/dropout rate table made by obtaining an addition/dropout rate of said feature points from a number of samples; (iii) an evaluating table in which types of predetermined feature points necessary for determining a word are written for each of a plurality of predetermined words; (iv) a feature point extracting portion for extracting feature points from input speech in accordance with the contents of said analysis procedure portion; (v) a similarity computing portion for computing similarity of feature points necessary between objective words by detecting the presence/absence of feature points with reference to said evaluating table and said addition/dropout rate table; and (vi) a determining portion for determining words by using said similarity.