This studyaims to reveal pragmatic property of plural expressions in Korean onthe basis of semantic plurality. Korean plural expression such as tul,ney have studied mostly on their semantic plurality. However,interesting phenomena are observed. That is, Korean plural expressionsserve as pragmatic markers which present honorific, modesty andnon-formality, even without plural reading in certain cases. To figureout the reason of this, I clarify plural meaning and pragmaticproperty of tul, ney, ttawi. Besides, it is considered that they aresystematically co-related. Thus I suggested plurality-informalitysystem schematically