This article examines and analyzes the Korean Supreme Court Judgements in 2009/2010 about bill of exchange, note and checks. It investigates four cases. The first case treats the problem about the reversion of the security money for accident notification that be deposited in a depositing bank at the time that a court sentences the bankruptcy against the corporation which is a drawer. But the decision by the court have no relationship with the security money, because the holder in due course is the first person who has the right against the security money. Therefore the depositing bank must pay the holder in due course with the money if he may be prove as the holder in due course by the procedures for bankruptcy. The second case deals with the problem about the relation between the debtor, who had endorsed over a bill for the security to origin debtor and the creditor. In this case, the decision of Korean Supreme Court regarded the behavior of the debtor, who had endorsed a bill for the security about origin debtor, as the behavior of guaranty at the Civil Law in Korea. Therefore, I concluded that the court`s decision in this case was rational. The third case treats whether the prescription of a inchoate instrument and the right to fill up could be interrupted by the fifing of a lawsuit, and whether the holder of a inchoate instrument could fill up at that time. The court`s decision in this case demonstrates that it is possible. The forth case deals with the problem about the relation between the completion of prescription and origin claim, and treats whether the debtor could offset the claim of the creditor by his claim for compensation. This problem depends on whether the debtor has received a real damage by the completion of prescription or not.