In terms of deregulation requests from business, incidents at construction sites are rapidly increasing after reducing the regular safety training hours. Especially, to prevent incidents through safety trainings for construction site workers, who have lots of hazardous tasks than general manufacturing, is not only to protect property of both the companies and the country but also to increase their profits. That is why there are loud voices regarding that the safety training is a core mandatory to prevent industrial incidents. But, most companies, as soon as the deregulation for safety training is implemented, mitigated conducting safety trainings to prevent incidents. With this, the incidents are currently to be increased and caught in a vicious circle of many incidents at the smaller companies because of their absentmindedness regarding safety training due to their poorness as subcontractors of major companies, comparing to major companies. This study explains that the difference between managers and workers are existing about safety awareness and knowledge. And, we confirmed that the educational factor led by deficiency of safety awareness and knowledge was the major factor.