The Online Digital Contents Industry Promotion Act was amended in 2005 to effectively protect users in online digital contents transactions. One of the main idea of the amendment is cooling-off rule. Under this cooling-off rule, the user who purchases online digital contents and later changes his or her mind, has right to cancel for a full refund until 7th business day after digital contents offer. But it has several exceptions like that if the user break shrink wrap, which is a plastic seal tightly fitting the software package, cannot claim the right. But the Online Digital Contents Industry Promotion Act has no unique provision for cooling-off rule and just has make Electronic Commerce Consumer Protection Act, which is focused on tangible things, to apply that transactions. Unfortunately this includes possibility to cause a lot of problems. It is because digital contents has the distinguishable characteristics from tangible things, which Electronic Commerce Consumer Protection Act applies. At this point, this article reviews how the cooling-off rule of the Online Digital Contents Industry Promotion Act operates on online digital contents transactions generally. Then this article considers what problems the cooling-off rule has when it applies to various types of online digital contents transactions. Lastly, this article concludes the Online Digital Contents Industry Promotion Act can cover the online digital contents transactions in part but it still has problems on applying to those transactions, so it need to be amended by making unique provisions for the unique characteristics of digital contents including the return of digital contents, the introduction of user concept etc.