The letter of credit is one of the imprtant promise to all parties, including the exporter, importer, and intermediary banks in the commerce. Therefore, as if I easily keep an appointment with my friend and cancel it, I can not change or alter the content of the letter of credit in my way during the trade. When the opening bank issues an letter of credit, he has to write clearly the article of “irrevocable” or “revocable” in it before he notify it. So, there are two type of the letter of credit according to “irrevocable” and “revocable”. Now, I will describe the differences between “irrevocable” and “revocable” letter of credit.