The purpose of this study is to investigate translation units with Korean-English parallel corpus. The main assumption of this study is that translation unit is a monosemous unit and has a translation equivalent which acquires more than 50 percent in a corpora, at least. We identified the translation units of frequent nouns(market and company) in the Korean-English parallel corpus that made of newspaper in order to inform an investigation of translation unit size. Findings of this study reveal that translation units and its translation equivalents are varied with its collocational structures. The single word market was regarded as a translation unit and the single word company also was regarded as translation units. Some attributes of translation units were revealed. The translation units did not affect singular and plural forms in translation equivalence. a/the forms are not affected as well. And we pay attention to the way that how the machine translator to be worked.