There are various conditions (radiation controlled area, special equipment, special rule and so on) in nuclear related facilities. When we work there, we are always required to achieve high level of safety, reliability and efficiency. We self-manufacture tools to eliminate unreasonableness (Muri), unprofit (Muda), unevenness (Mura) and also improve efficiency. Always aiming the improvement of safety and productivity is one of the important missions as a cooperating company. In this report, we introduce several cases of Kaizen effort of maintenance by tool production.