In this article, the author reviews the provision of presumption of collusion under the Monopoly Regulation and Fair Trade Act and suggests how to overcome the underlying issues raised by the provision. Part I addresses legislative policy on cartel regulation under the MRFTA. Part Ⅱ examines the provision of presumption ofcollusion under the MRFTA, which was adopyed in the amcndment of the Act to cffcctively attack tacit collusion. Then, it points out the possibility of harsh resuit on alleged cartel participants in a cartel case duc to the prcsumption provision. Whilc noting that it would be inappropriate to amend this provision because of such possibility and limit the application of it substantially, this article focuses its discussion on how to exercisc the presumption provision properly, thereby avoiding punishing innoccnt “violators” under thc MRFTA. Part Ⅲ compares the relcvant clauscs to presumption of collusion, Section 19 paragraphs 1 and 5 of the MRFTA, in analyzing the presumption provision of the law. Part Ⅳ further discusses the issue of “restraint of competition” in cartel cascs where the presumption provision is applicd. Part V analyzes a reccnt decision by the Korean Fair Trade Commission in which the Presumption provision was applied to acartel among ten apartment construction companies fixing the procc of condominium apartments. As a conclusion, Part VI reviews two requirements set out in recent KFTC`s cases for collusion to be presumed under the MRFTA, and proposes that respondents or defendants in allcged cartels of tacit collusion should be allowed to arguc justifications before the KFTC so as to relieve innocent “violators” by applying the presumption provision of the Act.