PURPOSE: A method for producing tetraploid oysters by combining cytogallacin B(CB) and 6-dimethyl aminofurine(DMAP) is provided to ensure effective production.CONSTITUTION: A method for producing tetraploid oysters which are able to grow comprises: a step of fertilizing an egg of triploid female and sperms of diploid male oyster a step of blocking release of a first polar body from the fertilized egg and a step of culturing the fertilized egg at 18°C to 30°C and 17 ppt to 33 ppt of salinity.COPYRIGHT KIPO 2012본 발명의 일 구체예는 사이토갈라신 B (CB)와 6-디메틸아미노퓨린 (DMAP)의 조합을 사용하여 4배체 굴을 효율적으로 생산하는 방법을 제공한다.