In this paper, I investigated the characteristic of Japanese Middle construction through relationships between Modal adverbs and Middle construction in Japanese. Firstly, we could confirm that the relationships have to do with genericity; Modal adverbs Kanarazu and Zettai allow the relationship with Middle, however, Modal adverbs Kitto, Osoraku, Tabun do not with Middle, even though they seem that the adverbs co-relate with Middle construction. Because the syntactic restrictions don't have to do with genericity. Secondly, Modal adverb Hyottoshite, Moshikashite, Doumo, Douyara do not with Middle, which they don't have to do with genericity, and the modal adverbs require auxiliary verbs. Thirdly, the modal adverbs Hyottoshitara, Hyottosuruto, Moshikashitara, Moshikasuruto, Tashika, Tashikani allow optionally the relationship with Middle; These syntactic phenomenons ralate to distress of the native speakers who judge the relationship between the modal adverbs and Middle. The native speakers tend to confuse Middle sentences relate with these modal adverbs are interrogative sentence, not declarative sentence. The Modal adverbs Hyottoshitara, Hyottosuruto, Moshikashitara, Moshikasuruto relate not interrogative sentence, but declarative sentence. Lastly, Modal adverbs Tashika and Tashikani do not relate with Middle. Because They have to do with Middle which have semantic characteristic of both generic and judgement sentence.