The purpose of this study was to examine the structure of students' knowledge formed in information education at junior high-school level. Seventy-two 7th graders (first-year junior high-school students) and 78 10th graders (first-year high-school students) participated in the study. A cluster analysis was performed on 40 items of knowledge that was included in "Information and Computers." The results of the analysis indicated that students' knowledge composed from the perspective of two clusters: "Practical knowledge" and "Systematic knowledge." In addition, "Systematic knowledge" was significantly correlated with "Processing ability," which is one of the subordinates to "the ability of practical use of information."