The present study examined gender differences in kindergarten students' ability for behavioural self-regulation and executive function in East Japan. One hundred and eleven 5-year-old children were assessed on behavioural self-regulation, inhibitory, and working memory tasks (direct measurement). Children's responses to the teacher's instructions were video-recorded and analysed (class room observation). Teachers assessed behaviour problems in the classroom. Results demonstrated that, while there were no significant gender differences in direct measurement or classroom observations, there were gender differences in teachers' evaluation of social problems, attention problems, and aggressive behaviour, with girls demonstrating lowere levels of problem than boys. These results suggest that teachers' evaluation of behavioural problem could be biased by gender. Possible reasons for this discrepancy were discussed.