The purpose of this meta-analysis is to analyze the difference of student achievement between charter schools and other public schools using standardized mean-change measures. Although many researchers have studied the effects of charter schools on student achievement, the results of those studies are mixed and unclear. According to this research synthesis of 395 mean-change effect sizes of 13 studies, charter school students' test scores over time are slightly higher than those of other public schools by 0.06 standard deviations. Furthermore, the results of fixed-effects regression analysis by duration reveal that the coefficient is positive. Although it is a small difference, this indicates that students' learning gains in charter schools are higher than other public schools.