PROBLEM TO BE SOLVED : To prevent real estate information managed by owners and a manager from being scattered and lost due to the transfer of the owners and the manager of pieces of real estate and also to conveniently provide an investor or a tenant with information of reliable pieces of real estate.SOLUTION : A center unitarily manages information of the pieces of real estate about respective objects, and the owner or manager of each piece of real estate registers, refers to and updates the information of the pieces of real estate at the center through a communication line 40. A role management mechanism 60 for managing the role of each company/individual and an access authority management mechanism 70 for defining access limitation in accordance with the role are provided in each piece of real estate to perform appropriate access control. The access authority of the participant of a piece of real estate such as an owner and a manger can be appropriately changed by changing the definition contents of the role management mechanism 60 when ownership is transferred due to dealings in real estate or the like and when mangers or management contents are changed due to the conclusion, change, cancellation, etc., of a management commission contract.