This paper deals with the structure and changes of dialect vocabulary and its general properties and rules. The words recorded in the dialect glossary “Shonai Hamaogi” (1767) are treated as a whole, and changes in the remnant rate and generational differences in modern times are considered. The interaction is analyzed through computational lexicology, using various transitions as clues such as frequency of usage, semantic field, and geographical distribution range. In terms of semantic field, many of obsolete words are related to living conditions of the time, such as tools. When looking at the nationwide dialect distribution, words that are used only in small regions tend to be lost, and words that are used over wide regions tend to survive, particularly colloquial and slang words in Tokyo. Social and cultural changes are the basis of vocabulary change, and as the outside world changes, so do words. The frequency of word usage changes depending on the field of meaning. This affects the size of the national distribution and controls the remnant rate. Owing to the expansion of the range of communication, words that are limited to a small region tend to be forgotten, and regional differences diminish. Using these concepts, vocabulary changes found over the 250 year period since the compilation of “Hamaogi” and surveyed across respondents spanning 140 years were understood in concrete terms.