This research is a series of studies to find out the differences between onomatopoeia and mimetic word in Korean which examined each inherent morphological characteristic with comparing morphological differences composing onomatopoeia and mimetic word. Main results are as follows. First, In part of speech, Onomatopoeic word is more varied than mimetic word Second, [Onomatopoeic word+-hada] is all verb, but [mimetic word+--hada] is a verb or an adjective. Third, Adverbial suffix `-i/hi` can not be combined with Onomatopoeic word Forth, In morphological terms, mimetic words are more stable than Onomatopoeic words.