This study aims to determine the regulation of sale and purchase transactions through LINE and the form of responsibility of business actors against breach that occurred in sale and purchase transactions through LINE. This research was conducted in Semarang city. This research is done by determining the respondents who will be given a questionnaire by broadcast message that is sending short message service to many destination. Then select the respondents who have made a sale and purchase transactions through LINE. The result of the research shows that the arrangement of sale transaction through LINE is not much different from conventional sale and purchase arrangement that is based on Article 1320 Civil Code and Article 47 of Government Regulation Number 82 Year 2012 on Electronic System and Transaction Management where the requirement is the agreement of the parties, the party making the covenant, certain things, and the lawful cause, only the transaction is done in the form of electronic transactions in this case through LINE while the responsibility done by the business actors if the practice of buying and selling done through LINE is to make replacement of goods, compensation, and give the deadline to the consumer to return the goods sent if not in accordance with the agreement.