An electric initiator is a component that is located in the thermal battery or propulsion unit to transfer energy first. Initiator tests include X-ray test, non-destructive leak testing, circuit/insulation resistance test, and CBT (Closed Bomb Test). Among them, CBT is a key element in evaluating the performance of initiator, and the reliability of the test results is important for judgment of the required performance. This study conducted inter-laboratory comparative tests to secure the reliability and repeatability & reproducibility of the initiator CBT. A comparative test was conducted with a mass production acceptance test agency to verify whether the reliability was secured.