With the development of information and telecommunications technology today has resulted in increasingly diverse also a variety of services-only existing telecommunications facilities, as well as the sophistication of information technology products that can integrate all the information media. Human computer as a tool, supported the development of technology to make the trade to be smooth and easy to be accessed by any person or company. Problems in this study is how the principle of responsibility of the offender Usha electronic transactions seen from kontrak.Metoda law used in this research is normative juridical and conducted a descriptive analysis with a qualitative approach to look at and analyze the legal norms (normative analysis) in the regulation legislation ada.Hasil obtained that responsibility industrialist applicable law is the principle of accountability for negligence, but in accordance with its development began to shift in the application of strict liability, especially in transactions that have a great impact risk. While in UU ITE is accountability businesses in principle Presumed liability for businesses that are in the wrong position so charged to compensate as a form of responsibility. Keywords:Electronic Transaction, Bussinesses, Responcibility Principle, Law of Contract. Information Technology.