The aim of this study was to investigate the psychological impact of colored classroom walls on individuals. The research was conducted with eighth-grade students from an international school in Chiang Mai, Thailand. A total of 34 students with a variety of cultural backgrounds participated in this study. Students attended their regular classes with the three wall colors of purple, green, and red, while the Bourdon Attention Test was utilized as an assessment of the students' attention level. Data from the two conditions, control and experimental groups, each consisting of both pre-test and post-test, were collected and examined to find out the effects of different wall colors on the student's attention. The results indicate that the classroom with red-colored walls showed a significant impact on the participant’s attention. In summary, this paper will contribute to enhancing awareness of how wall colors in educational facilities affect student’s learning activity as well as to assist future designer’s decisions on the usage of appropriate colors.