本論文旨在根據語料庫所得到的語詞搭配相關資訊，分析日文類義語「下降」與「低下」之語義以及用法的差異。 分析的結果發現，「下降」是主體動作動詞，在描述空間領域時，用來描述主體的「下方移動」、「虛構下方移動」以及事物的「幅度縮小」。而「低下」是主體變化動詞，專門用來描述事物的「幅度縮小」。 在描述抽象領域時，「下降」會以不具有程度性之事物為主體，表示其主體在某種「尺度上的下方移動」；以具有數量或份量上的程度性之事物為主體時，則表示主體本身在數量或份量上的「幅度縮小」。「低下」主要以具有程度性之事物為主體；包含數量或份量，以及在性質或品質相關名詞，表示其量或程度上的「幅度縮小」。 另外，動詞「下降」經常與描述動作過程以及動作的樣態之修飾語句一起出現，而動詞「低下」則是經常與描述變化結果的程度、變化的幅度等修飾語句一起出現。當「下降」「低下」做為名詞時，「下降」後面會經常出現描述動作過程以及動作樣態的後綴詞與動詞，而「低下」後面則經常出現描述變化幅度的後綴詞以及表示產生變化或防止變化產生的動詞。

The purpose of this study is to analyze the meaning and usages of the synonyms “kakou” and “teika” based on collocational information. As a result, “kakou” is an activity verb, and on space-domain it means the downward moving, the fictive downward moving, and the width reduction of subject; “teika” is a mutative verb, and it only means the width reduction of subject. On abstract-domain, “kakou” means the downward moving on a degree scale when the subject doesn’t have the degree characteristics; “kakou” also means the quantity reduction when the subject has the quantity characteristics. On the other hand, “teika” means the quantity reduction or the decline of the degree, and the subject of “teika” usually has quantity characteristics or degree characteristics, In addition, “kakou” often co-occurs with modifiers, suffixes and verbs which describe the process and the state of activity. On the contrary, “teika” often co-occurs with modifiers and suffixes which describe the result of variation or the variation in the width; “teika” also co-occurs with verbs which mean the occurrence of variation or avoiding the variation.