Occupational accidents and diseases remain the global health problem, two main factors for this are unsafe behavior and conditions. Previous study proved that the main cause is unsafe behavior factor. This study aimed to analyze factors associated with occupational unsafe behavior in workers at PT IAW and analyze the most influential factor. A cross-sectional study was conducted from July to August 2016 with 104 samples. Independent variables consisted of perception, communication, supervision, the availability of personal protective equipment (PPE), training and workplace temperature. While the dependent variable was unsafe behavior. Data analysis used Pearson product moment and multiple linear regression. In conclusion, perception (p value=0.00, R=0.817), communication (p value=0.000, R=0.810), supervision (p value=0.00, R=0.529), availability of PPE (p=0.000, R=0.902) and workplace temperature are related significantly, very strong, positive and directly proportional to unsafe behavior, while training (p value=0.092, R=0.166) are not related. Perception is the most dominant variable influencing unsafe behavior.