This paper aims at revealing the characteristics of the Japanese heasay “んだって (ndatte)”, focusing on the grammatical and semantic features. The summary of the main characteristics is as follows. First, different from a quotatve usage of “んだ･って”, in hearsay, “んだって” becomes formalized and is used as a modality which expresses the speaker’s attitude, and it serves a similar function as “そうだ(soda).” Secondly, unlike a quotation, the original speaker and time and space are not clear. The original speaker can be either explicit or non-explicit in the sentence, but it is often not-explicit. Thirdly, “んだって” has pragmatical usage expressing and . This paper also discussed on the function of “のだ” from a pespective of . When “んだって“ is in the , it explains the cause or reason of the preceding descriptive sentence, and it has two functions of hearsay and explanation. However, ”んだって“which is outside of the , it has only the function of hearsay, which often can be seen in usage.