PURPOSE : A system for electronic commerce in the apartment installment sale right using the Internet is provided to let a user check all particulars of an apartment installment sale right with a mouse click at home by specializing the electronic commerce on the Internet and to secure reliability in the transaction by mediating the transaction via a licensed real estate agent.CONSTITUTION : The system comprises a client terminal(10) to register as a member and request for buying an apartment sale right, a seller terminal(20) to register as a member and request for selling an apartment sale right, a server(40) connected to the client terminal and the seller terminal via a communication network(30) to guide member registration and electronic commerce and offer the information about an apartment sale right, a member database(41) to store the information of members, an article for sale database(42) to store the sale information, a purchase application database(43) to store purchase information, and an information database(44) to store the information related with financing, taxes, laws, apartment sale, and an apartment sale right offered by the server. The apartment sale right is transacted by auction.? KIPO 2002