Active commuting to school is an opportunity for carrying out physical activity and is associated with improved cardiovascular profile in children and adolescents. Within the field of Public Health, it is essential to better understand potential barriers that prevent children to choose an active form of transportation when going to or coming back from school. The aim of this study was to analyze the reliability of a questionnaire on barriers to active commuting to school in children. The sample of the study consisted of a total of 163 participants aged 9 to 12 years, enrolled in a school from Granada (south of Spain). Participants completed a questionnaire on barriers to active commuting to school twice during the spring of 2011, with an interval of 14 days between test and retest. In order to assess test-retest reliability, we calculated kappa coefficients considering the whole sample, as well as separated by gender and school year. Confirmatory factorial analysis was employed to test the instrument’s validity. Results showed that test-retest participants’ responses’ degree of agreement ranged above 0.40 (moderate to good reliability). Similar results were obtained repeating the analysis by gender and by school year. The presented questionnaire of barriers to active commuting to school is a reliable tool that allows to understand school children’s opinions regarding the mentioned behavior.