日文句末中的丁寧體否定形有「～ません」與「～ないです」兩種形式。形成時期是「～ません」＞「～ないです」，但是在用法等方面感到有所不同之處，所以進行了這兩語的比較與檢討。在日本語學上，有句型的成立與發展之考察，還有語言資料庫 (Corpus)‧小說‧劇本及電視節目等等的共時性調查；從日本語教育的觀點來看有學習者的發話等分析。在分析的觀點上雖然有書面語及口頭語還有改正度等等，卻也是現在變化仍持續進行中的事象。本研究是關於「～ません」「～ないです」，基於上述之複數類型的動向上，調查了收音機節目及劇本。在劇本之中，「～ません」較多，而收音機節目裏則是「～ないです」較多。在前接語的部分，有動詞接「～ません」，イ形容詞及名詞接「～ないです」之傾向。在後接語的部分則是斷言或接續助詞等等接「～ません」，終助詞則是接「～ないです」較多。雖然隨著話者不同會有若干的相異之處，但是在語彙選擇的傾向上，也可以被視為是受到說話方式的態式所影響。還有，作為今後這個分野的研究使用收音機節目是有效的也一併記述。

There are 2 forms "-masen" and "-naidesu" in Japanese polite negative form. It appears "-masen" earlier and "-naidesu" is the back. But the difference is found in usage and these two words of comparison and consideration are performed. On Japanese linguistics, there is researches consideration which are formation and a change, investigate corpus, novel, the scenario and the TV program etc. Synchronic Linguistics. There is an analysis of learner's utterance from the angle of the Japanese-language education. By the view of the analys is, there are written language, spoken language and a formal degree. But it's the phenomenon which also continues changing present. In this research, a radio program and a scenario were investigated about "-masen" and "-naidesu", after being based on the trend of the plural genre like the above. It has a lot of "-masen" by a scenario and have a lot of "-naidesu" by a radio program. In front of the word, it is a tendency that "-naidesu" attaches to a verb, and "-naidesu" attach to i-form adjective and Noun. In back of the word, it is a tendency that declaring and a conjunctive particle attaches to "-masen" an ending particle attaches to "-naidesu" There is difference by the speaker for a short while. Influence by a style of the way of talking is also considered by the tendency of the choice of vocabulary.