In this study, we used the K-CESA global competency test data to conduct the differential functioning items analyses and to explore their implication. The purpose of this analysis is to find out the implications for making and reviewing the items by examining the differential functioning of the items according to sex, grade, school, and school type. Overall, it was found that the construct measured by current global competency tests was mainly influenced by knowledge and memory competence on world history and geography. For detecting differential item functioning, likelihood ratio test and logistic regression method were used respectively. As a result of differential item functioning analyses by both methods, out of the total 30 items, 5 to 14 items appeared to have differential item functioning. An in-depth analysis of these questions was conducted through expert consultation. As a result, it was found that female students tend to focus more on fields of interest related to world history and geography than male students. Also, there was a tendency that the students in the area of liberal arts were superior to the students in the natural science. This was presumed to be due to the fact that they could be more exposed to world history or geography as elective subjects at their high school lives.