This study is subject to Byeongyeongseong(兵營城) in Kyungsang province(慶尙左道) in the era of Joseon dynasty and its purpose is to discover the process of transformation of traditional castle garrison into modern city. The result of this study shows that Ulsan Byeongyeongseong which was a military base where Byeongmajeoldosa(兵馬節度使) stayed used to function as a sole castle garrison with its higher population than Eupchi(邑治) in Ulsan dohobu(蔚山都護府) and was comparable to Eupchi in terms of urbanization. Of 1907, but Byeongyeongseong, as military capabilities had completely gone and facilities in the Japanese colonial rule focus on Eupchi, A function of the urban dropped significantly and the impact of the reduced population density was checked.