This article is aimed at examining the reason that why poems on department store by Yi Sang, Kim Gi-rim, Kim Gwang-gyun had a unique form, avant-garde style. Being based the relation cultural semiology with poetics, we can understand that reason successfully. Yi Sang`s avant-garde poem, “AU MAGASIN DE NOUVEAUTES” began with a chain of sentence having several `of`s; “a square of the inside of a square of the inside of a square of the inside of a square of the inside of a square(四角의內部의四角의內部의四角의內部의四角의內部의四角)”. We call this sentence style the uroboros-expression. The uroboros-expression has the effect of demolishing the border of two concepts and deferring it`s final meaning. This expression is a Yi Sang`s favorite style. Why this expression had emerged in poems on department store? Cultural semiology will give to us the answer. The uroboros-expression came from a labyrinthic form and the arrangement of department store which all were cut down by square figure. Cultural-semiology gave Yi Sang`s avant-garde poetry concrete forms and senses. The metaphysics of department store come from confusing experiences by following a labyrinthic guideline in department store is similar to the poetics of avant-garde arts. So poems on department store had a similar style, regardless of poet`s intention.