Abstract: NWB-CMS Brassica oleracea has cytoplasmic male sterility. It relates to NWB-CMS cabbage plant having cytoplasmic male sterility derived from NWB-CMS cabbage line produced by fusion between protoplast of NWB-CMS radish line plant derived from callus of NWB-CMS radish line having cytoplasmic male sterility with inactivated nucleus and protoplast of male fertile cabbage plant with inactivated cytoplasm and a seed thereof, a plant of NWB-CMS Brassica oleracea line having cytoplasmic male sterility produced by breeding of a male fertile Brassica oleracea as a subject for introduction with the NWB-CMS cabbage plant as a breeding line and a seed thereof, a method for producing a hybrid seed of NWB-CMS Brassica oleracea line having cytoplasmic male sterility comprising breeding of a male fertile Brassica oleracea as a subject for introduction with the NWB-CMS cabbage plant as a breeding line, and a hybrid seed of NWB-CMS Brassica oleracea line produced by the method.