Although the payment system has hitherto been recognized as an exclusive domain of banking companies, the government reportedly plans to help the securities industry to break down the wall of this domain for the purpose of promoting the level of customer service. The entry of the securities industry into the payment system or permission to payment function for security account is unprecedented in the world. The problem of payment system is not subject to public regulation by the policy or legislative powers. The payment system should be designed by all participants and administrated by private autonomy. Entry of securities industry into the payment system can be resolved by contractual agreement. But this subject arouses a few problems as follows. The understanding that banking companies are exclusively in charge of the payment system is derived from the fact that banks are the unique institutions in charge of deposit accounts. The government lays various kinds of prudential regulation against banks to protect deposited currency and to reach the goal of financial stability. Typical among them is the regulation on the scope of the banking business. So to grant permission for the securities industry to enter into the payments system while restricting access to banking companies in business area is unfair. The principal is usually not guaranteed in securities accounts. When securities accounts are used as the means for payment, that can bring about system risk. That is why banking companies are exclusively in charge of the payment system. Should the entry of the securities industry into the payment system be permitted in spite of these reasons, the following conditions should be resolved. When securities accounts are used as payment transaction accounts, they should be considered as bank accounts and the institution dealing with these accounts should be supervised as banks. The payment system is subject to oversight from the central bank. The main purpose is to prevent and resolve payment risk to maintain the stability and efficiency of payment system. Accordingly, when the securities industry is permitted to participate in the payment system and securities accounts are considered to be bank accounts, the securities industry should be subjected to oversight from the central bank. The topic of universal banking needs to be discussed in more depth. Because the cause of restriction in business area of banking industry can be recognized as the price of exclusive charge of bank accounts and payment system.