In recent years, automation of mining equipment has been required to improve productivity, predictability, and safety of mining operations. Some major mining companies have begun efforts to automate dump trucks that transport overburden and minerals, eliminating the need for human operators, aiming for reducing labor costs, increasing operating hours, and improving efficiency of vehicle assignment. It is called an autonomous haulage system. The introduction of an autonomous haulage system requires significant changes in operations management. Particularly, safety needs to be carefully considered. Conventionally, in manned mining operations, ensuring the safety while at work has largely been the responsibility of site managers, fleet controllers, machine operators, and field workers. However, when making the machine unmanned, it is necessary that the system bears a part of the function for ensuring safety, which has been conventionally carried out by humans, and that the user appropriately understand and operates the system. This paper describes the concept of ensuring safety when applying an autonomous haulage system using unmanned dump trucks to mining operations, and a system architecture based on it. First, we proposed the basic structure of the autonomous haulage system, conducted a risk assessment assuming mine operation using the system, and identified possible protection measures. Next, we examined the architecture of an autonomous haulage system with a safety function that enables more deterministic performance evaluation while considering the complexity of the system. This system was installed in an actual mine site, tested and operated, and it was confirmed that the safety functions worked properly. When introducing the system, the safety concept and architecture of the system have been explained to the site safety manager and governmental regulators and have been validated.