The current study aimed at investigating the effectiveness of an international field experience on the metacognition in Korean elementary pre-service teachers. To accomplish the purpose of this study, a pre- and post-test research design in one group was constructed and surveys were conducted before and after the international teaching practicum which was carried out in the United States. The preliminary survey was conducted from January 8 to 12, 2018, and the post-survey was conducted from February 23 to 27 after returning home. Participants were 49 pre-service elementary school teachers in the second and third grade at one university of education which is located in the midland of Korea. Data were analyzed by using the paired t test and the repeated measure one-way ANOVA, with SPSS 21.0. The findings were as follows. First, the total score of pre-service teachers metacognition significantly increased after the practicum. It indicates that the international filed experience has a positive influence on pre-service teachers metacognition. Second, there were significant increases in all five sub-factors of metacognition (i.e., metacognition-knowledge, monitoring, experiences, skills, and management technique by level). In addition, all scores of the question items in each of the sub-factors significantly increased. Third, the second grade pre-service teachers showed larger increase in metacognition than the third grade pre-service teachers, although there were significant increases in pre-service teachers metacognition for both grades. Based on these findings, several implications and suggestions were discussed. The results of this study are expected to be used as basic information for the research area of international teaching practicum by empirically analyzing the effectiveness of an international field experience on the metacognition of elementary pre-service teachers.