The welds of piping used in domestic nuclear power plants are suggested to form more than a certain amount of delta ferrite in order to prevent high temperature cracking. However, it was experimentally investigated whether the high ferrite content could induce thermal embrittlement and the thermal embrittlement affected the residual stress. Unlike the expectation that heat embrittlement will not affect the welding residual stress, we found that the welding residual stress is lowered. In order to confirm this, the residual stress of austenitic stainless steel plate welds was compared before and after thermal stress.