The present invention relates to a comparative trading system through verification of real estate for sale, which blocks fake real estate for sale through verification of real estate for sale to increase reliability of listing information, and a method thereof. Moreover, the present invention relates to a method, which collects a plurality of pieces of verified information about real estate for sale to provide a real estate comparison service and provides a comparison service newly registering or updating information about a product to be compared through collection of information about products of interest, and a system thereof. According to the present invention, the method comprises the following steps : allowing a real estate comparison service server to request the information about products of interest of a buyer stored in an online server; allowing the online server to extract and transmit the information about the products of interest requested from the real estate comparison service server to a price comparison service server; and allowing the real estate comparison service server to provide a real estate comparison service about the corresponding product of interest by using the information about the products of interest received from the online server. Accordingly, a real estate seller confirms reliable information about real estate for sale through a listing confirmation system of his own with an aggressive posture, thereby providing rewards to an information registrant providing reliable information about real estate for sale. Moreover, the reliable and valuable information about real estate for sale is collected in such a way that it can be compared and searched, thereby increasing reliability for customers in internet real estate brokerage.