Currently, the high demands and needs to improve productivity and labor-saving in construction industries leads to many automation and mechanization. This report aims to address the shortage of skilled worker in the future as well as improvement of safety, productivity and quality. Comprehensive collection and utilization of information were carried out and with target to eliminate the over reliance of experience worker in mountain tunneling, "Automated Angle Control System" technology was developed to reduce the overbreak of tunnel during excavation. The concept of this method is to ensure that the productivity of drilling for blasting operation will not be influenced by the worker skills. This system was tested in Shin-Tomei Expressway Takatoriyama west tunnel construction project and results confirmed that the system successfully minimized the overbreak of tunnel during excavation. The authors hope that this report will contribute to the improvement of safety and productivity.