Attitude plays a great role in student's learning behavior. This study was designed to investigate the contributions of classroom environment to students' attitude toward math. Participants in this study were 70 students of Etika Dharma Catholic Junior High School in Surabaya. Classroom environment was measured using adaptation of what is happening in This Class? (WIHIC) scale and attitude toward math was measured using a scale developed by the researcher. The result shows that there is a significant positive correlation between classroom environment and attitude toward math (r = 0,359, p < 0,01), which means the more positive students' perception of their classroom environment, the more positive their attitude towards math would be. The linear regression analysis shows that classroom environment effectively contributes 12,9% to students' attitude toward math (r 2 = 0,129). Classroom environment can be used to predict students' attitude toward math, with the equation Y = 48,916 + 0,229 X ± 23,023. Result shows that classroom environment has a significant influence on attitude toward math, although not too significant. This is due to the existence of other variables that may influence attitude toward math, such as achievement, peers, teacher, and other environmental factors.