This paper examines the tendency of the Japanese epistemic adverbs of certainty in the texts of the Meiji and Taisho periods(1868-1926) from the stylistic features and differences by the “Corpus of Historical Japanese Meiji-Taish? Period Series”. As a result, Japanese epistemic adverbs of certainty were frequently used in the colloquial style as an overall feature. In addition, Japanese epistemic adverbs of certainty were classified into more colloquial adverbs(e.g. okata ‘presumably’, kitto ‘surely’, sazo ‘surely’, sadameshi ‘presumably’, zettai(ni) ‘absolutely’, tashika ‘certainly’, tabun ‘perhaps’, domo ‘likely’, doyara ‘likely’, masaka ‘surely (not); unlikely’, yomoya ‘surely (not); certainly (not)’), more literary adverbs(e.g. kanarazu ‘surely’), and adverbs used in both literary and colloquial type(e.g. osoraku(wa) ‘probably’), and there was a substantial difference in the tendency by literary and colloquial style in each word. Furthermore, there was also a comparison of the stylistic characteristics of each genre's appearance trends and synonymous words (e.g. osoraku(wa) and tabun). Based on this survey, it is necessary to analyse and clarify the tendency of stylistic usage of compound adverbs(e.g. kotoniyoruto ‘possibly’, hyottositara ‘maybe’, mosikasureba ‘maybe’)...