A customized online system for a real estate intermediating business is provided to activate the use of an existing site for a real estate intermediating business by connecting a card cyber branch provided by a financial institution to a site for the real estate intermediating business provided by the financial institution through a network. A customized online system for a real estate intermediating business comprises the following units. A customized card for a real estate intermediating business is applied through a card applying unit(110) on the internet. An online card is approved through an affiliated store applying unit(120) as a card-affiliated store. A card cyber branch(130) provides a customized card service for the real estate intermediating business.