PROBLEM TO BE SOLVED : To provide a registration information processing system for contributing to the smoothing of various tasks derived from a change in registration information.SOLUTION : A registration information processing system 1 includes : a registration application information acquisition RA for acquiring registration application information indicating that the application of registration has been made; a registration information acquisition part RI for acquiring registration information on the basis of property specification information for specifying real estate corresponding to the registration application information; a registration change determination part VF for determining whether or not any change satisfying predetermined conditions has been made in the registration information of the real estate specified by the property specification information on the basis of at least either the registration application information or the registration information; and a registration related information output part IG for outputting at least a part of the registration information of the real estate specified by the property specification information determined to satisfy the predetermined conditions by the registration change determination part VF as registration related information.