A common rail is provided for promoting inner pressure fatigue strength at location in proximity to a branch pipe. The common rail includes a main pipe rail with a main flow path. At least one boss in provided on the peripheral wall and includes a branch hole communicating the main flow path. The branch pipe is provided with a connecting head that has a pressing face at and end of the branch pipe. The pressing face of the branch pipe is urged into a pressure receiving seat of the boss. A compressive residual stress is provided at location in the peripheral wall where the main flow path of the main pipe rail communicates with the branch hole. The compressive residual stress increases the pressure fatigue strength by substantially canceling tensile stress.