The purpose of this article is to study the diachronic change of so-called unusual locative case maker in the latter part of the Middle Korean. The locative case maker ‘-□/의’ in the latter part of the Middle Korean attract academia attention and was named ‘unusual locative case maker’ by the contentions these it always needed particular preceding nouns. Meanwhile, some papers insists that the shape of unusual locative case make is always ‘-□/의’ from Ancient Korean to Modern Korean. However, according to research outcome, ‘-中(十)’ in Ancient Korean can be restored ‘*-□/긔’ and ‘-矣/衣’ is not a writing for ‘-□/의’ but same writing with ‘-中’ in Hyang-ga(?歌) on Ancient Korean. If we compare ‘上十’ in the Gu-gyol(口訣) for the Korean reading on 13c with the change of phoneme ‘ㄱ>ㅎ>ㅇ’ from 11c to 14c and ‘우희’ on 15c,we could read ‘上十’ to ‘우희’. Also, considering the reading sounds of ‘-哀’와 ‘-□’ in Gu-gyol for the reading Chinese character phonetically from late 13c to 14c, the shape of unusual locative case maker on this times is same with the unusual locative case maker on the latter part of the Middle Korean On 18c, the phoneme ‘·’ had been disappeared. This change affect the form of case makers and endings in Korean language and the shape of ‘-□/의’ had changed to ‘의’. The unusual locative case maker ‘의’ on Modern Korean had been used until late 19c and it had disappeared on early 20c. To conclude, the so-called unusual locative case maker had changed diachronically like ‘-□/긔>-□희>□-의>-의>ø’