This study looked at Korean elementary school students' performance in inquiry-based science by subjecting Korean sixth graders to Japanese national standard science assessment items. The purpose of this study was to assess the Korean science curricula and to compare the two groups' level of inquiry. Also this study not only compared the science achievement of Korean and Japanese students, but it also Received(June 24, 2014), Review request(June 25, 2014), Review Result(1st: July 07, 2014) Accepted(December 10, 2014) Publish(December 31, 2014) 660-759 Dept. Science Education, Chinju National University of Eduction, Shinan-dong, Jinju, Gyeongnam, Korea email: ytkong@cue.ac.kr * This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2013R1A1A2004851). Comparison of Korean and Japanese elementary school students' achievement on inquiry-based science assessment items Copyright c 2014 SERSC 202 compared the two nations' assessment of academic achievement in science. The results are as follows: (1) Science curricula in both Korea and Japan stress the importance of inquisition; moreover, Japanese science curriculum tends more to emphasize scientific-inquiry aptitude that is progressively connected within in grade level hierarchy. (2) Much like their science curricula, the two nations' assessment both stress importance of retention and conceptualization of inquiry-based science to strengthen future competence. (3) Students' inquiry-based science capabilities were evaluated by contrasting at the accuracy rates of responses across different types of items. (4) Both Korean and Japanese students had a difficulty for applying and describing the concepts and terminology used in science. Students of both nations also had problems organizing and assessing experimental results. This study has implications for managements in both Korean national-standard study achievement and the recent science education curriculum.