In the current information society, the need for securing human resources acquired with ICT competency is becoming a very important issue. In USA, England, Japan, India and Israel improving students' ICT competency has become a pedagogical issue. Accordingly, education on ICT competency is changing in many countries emphasizing the basis of computer science. The Korean government revised the ICT curriculum of 2001 focused on the basic concepts and principles of computer science as educational policy in 2005. However, it is still difficult to determine a student's ICT competency level and the outcome of ICT curriculum based on changed direction. Thereupon, this study has developed test tool for measuring the level of Korean elementary school students' ICT competency based on computer science. In this study, 'Content' and 'Information processing' are established as the two axes of the test frame standard through literature research, consideration and discussion. The validity and reliability of questions are verified though the preliminary test and the main test tool has completed through question revisions considering the distribution of answers. About 40,000 students, roughly 1% of the total elementary school students, are selected for the main test. There were several findings made in this study. Korea's elementary school students have a weakness in "algorithm and modeling". Information processing stage has been found to vary by grade. A modified "Angoff method" is used to confirm the spread of the ICT competency levels of the target students. From the results, the cutoff score employed to divide the subjects into three levels, excellent, average and below average, the ratio of excellent levels decreases and the ratio of below average increases in higher grades. To solve these problems, we need to emphasize algorithmic thinking oriented more principal of computer science in ICT curriculum. For more effective ICT elementary education, teaching and learning strategies appropriate for young children to teach computer science should be introduced. (Contains 18 tables.)