As electronic commerce brisks up, enormous number of and various types of internet shopping malls are open and prosperous. The Meta-Malls architecture was introduced to take the advantage of economy of scale and to allure consumers with plenty of commodities. Security of order information and payment instruction is also a buzzword in shopping malls based on the Meta-Malls architecture as in other kind of shopping malls. The security problem is, however, much more complicated in the Meta-Malls architecture due to the characteristics of the architecture. This paper suggests a security architecture which ensures the secure transmission of order information and payment instruction among customers, merchants, and financial institutes by introducing the concept of payment representative. The objectives of the security architecture are confidentiality, authentication, integrity, and linkage. To achieve the objectives, the architecture defines several additional encrypted messages between the payment representative and the shopping malls in the meta-mall based on SET (Secure Electronic Transaction), which is a de facto standard in the field of electronic commerce. This architecture was implemented for a Korean shopping mall which is running business.