This article aims to examine allomorph alternation of ending depending on part-of-speech. For meeting this purpose, this study considered carefully some types of endings whose morphs are alternated depending on part-of-speech. The distribution of these endings could not be delineated as a single one: phonological condition or morphological condition. The most of cases were that many conditions acted in combination. - namely, they are divided into two types and then some of them is explained by phonological or morphological condition. As a result of examining the distribution, only some of them can be defined as allomorph relations. The meaning of grammatical morphemes like endings is the dependent meaning decided by the element coming before or after. Therefore the meaning have no option but to change if the grammatical categories of the element coming before or after are changed. Owing to these reasons, it is difficult that the information of part-of-speech is referred when allomorphs are alternated. In conclusion, the conditions of allomorph alternation in Korean are left as two: phonological condition and morphological condition.