An information processing system including at least one computer that is connected to an equipment unit via a network is disclosed. The information processing system includes a reception unit which receives data via the network; a data storage unit which stores the data; a first transmission unit which transmits, to the equipment unit, the data in response to a request for obtaining the data stored in the data storage unit from some equipment unit; a history information storage unit which stores history information on transmission of the data by the first transmission unit and on reception of the data by the reception unit; a projection unit which projects a first equipment unit which transmits the obtaining request on first data in response to the reception of the first data by the reception unit; and a second transmission unit which transmits information on the first data to the first equipment unit.