This article is an attempt to confirm what was in the background of emergence of "The theory of Imna-Daemado". This theory, which has recently been raised again by some historians and misleads the public, was started at the research of Mun Jeongchang and Lee Byeongseon. Their claims are based on several records of Nihonsyoki. However, there are historical records of Korea that can exclude their claims. The method of history is to cross-validate these historical records to reach the truth. However, they attempted to settle the problem by excluding or concealing part of the records which is against their claim. Their conducts show that there is an intended purposes in their research. It is hard to regard this as a result of each individual researcher's ambition. On the basis of so-called "Territorial Purism", they tried to exclude the colonies of other states in the historical area of Korea and to create our colonies in the historical area of Japan. Consequently, Imna was colonized by ancient state of Korea established in Tsushima Island. This provides the fact that colonialism which changed only subject holds place inside their researches.