Many of the robots developed so far, including our multi-axis bone cutting robot, use an end mill as the cutting tool, and some problems should be solved to apply them to the minimally invasive orthopedic surgery. Minimally invasive surgery makes the incisions smaller, reduces pain and trauma to the body, and enables faster recovery. The smaller incision means a small and narrow opening area. This means the robot attitude for the bone resection is restricted, and it can result in the collision of the tool with the surrounding tissue, the existence of an untouched area and the degradation of the joint position accuracy. This paper proposes a robot mechanism and a toolpath generation technique specialized for bone cutting is expected to resolve these issues.