Objective: We investigated how students' interest in healthy eating changed after the introduction of on-site school lunch, prepared on campus, at a Japanese junior high school. Design: One-year follow-up study. Setting: Participants were 166 students in their second year of study at a public junior high school in Japan which introduced an on-site school lunch programme instead of students bringing lunch from home. Method: Students' interest in healthy eating habits was evaluated using the Japanese Questionnaire of Consciousness in Dietary Life for Adolescents Form (JQCDL-AF). Results: Data from 139 students who completed all three surveys were analysed. Total scores after 1 month increased significantly compared to baseline. This increase was sustained among boys 1 year later. The introduction of on-site school lunches is an effective strategy not only for providing healthy meals but also for increasing interest in the development of healthy eating habits. Conclusion: Increasing opportunities to get involved in meal preparation through the introduction of on-site school lunches may be an effective means of facilitating healthy eating among students.