Letter of Credit between buyer and seller in International Trade Transaction is the means of payment which makes International Trade operate smoothly by guaranteeing an exporter against non-payment and an importer against non-delivery. Therefore, the parties to a sale apply UCP500 established by the International Chamber of Commerce, in accordance with principle of the freedom of contract among the parties concerned, to look to their own legal stability. However, we may recognize some cases to have been applied principle of faith and trust, one of the dominant principles of the civil law, by the Korean Supreme Court and other cases to have not been applied that principle by the Korean Supreme Court. The Court shall apply UCP500 strictly as long as the parties concerned adopt UCP500 in view of the legal stability. In other words, in case that the Court applies principle of faith and trust to the case related to L/C, this rule - principle of faith and trust - should apply to the subject matter which have not stipulated in UCP500 under certain restriction. We suggest keeping in mind points to korean companies as follows; First, the parties to a sale shall understand L/C basis transaction and principles related to L/C deeply. Second, the exporter shall prepare documents in compliance with L/C and fulfil his or her obligation according to UCP500 and L/C related to the contract. Third, as buyer or importer, when he or she receive the shipping documents with discrepancies from the notifying bank, he or she makes him or herself clear to all the parties concerned. Fourth, as bank, she shall examine all the documents according to UCP500 and L/C related to the contract, and if any document with discrepancies, the bank, by all means, shall approach applicant first, and then decide whether to pay the credit amount to beneficiary or not to.