PROBLEM TO BE SOLVED : To provide a real estate transaction support system that reduces a burden of a user considering a purchase of a real estate or a lease contract thereof and a burden of a real estate agent in a real estate contract.SOLUTION : The real estate transaction support system connected to a user terminal UT via a network is configured to include : a user information DB20 that, for each customer ID, stores customer information on a customer and a desired condition of a real estate property under consideration by the customer in association with each other; a property information DB30 that, for each property ID, stores agent information on an agent dealing with the real estate property and non-disclosed property information to be identified by the property ID in association with each other; and an information providing part 13 that provides various pieces of information to the user terminal UT. The information providing part 13 refers to the user information DB20 and the property information DB30 and, for each customer, searches for the non-disclosed property information satisfying the desired condition of the customer and transmits the agent information dealing with a property of the retrieved non-disclosed property information to the user terminal UT.