The purpose of this study is to find a way to improve the lexical competence of 5th graders in elementary school through role-play activities. Role-play activity is an integrated-language teaching. To accomplish the objective of this research, six classes of M elementary school in Seoul were selected and divided into two groups. For three periods, the experimental group was given lessons using role-play activity while the control group was given lessons using text book consisting of segregated language skills. To measure the effects of improvement of lexical competence, four modes of tests were introduced for pre, post and delayed test. The result shows that integrated language teaching is helpful to improve learners’ English lexical competence in delayed test. It implied that learners can enhance their vocabulary acquisition and retention through integrated language learning. According to the analysis of test, the experimental group showed better achievement in active recognition and active recall. It indicates that skills-integrated class can improve students’ active mode. The tendency observed in the study shows that if skills-integrated instructions are continued on to the students, the positive effects of experimental group will be more apparent statistically.