A data sharing system including a first information processing apparatus (Node A) that stores original data, a second information processing apparatus (Node B) that acquires duplicated data of the original data from the first information processing apparatus (Node A), and a third information processing apparatus (Node C) that is capable of communicating with the first information processing apparatus (Node A) and the second information processing apparatus (Node B) is a network, the second information processing apparatus (Node B) comprising a duplicated data-transmitting unit adapted to transmit the duplicated data acquired from the first information processing apparatus (Node A) to the third information processing apparatus (Node C), and the first information processing apparatus (Node A) comprising: a first storage unit adapted to store original data; a generation unit adapted to generate duplicated data of the original data; a - second storage unit adapted to store a list for managing information processing apparatuses that store duplicated data of the original data, the list including, in a manner associated with each other, data names of the original data, node information indicating the information processing apparatuses storing the respective duplicated data, and node statuses of the information processing apparatuses concerning the respective duplicated data, wherein the first information processing apparatus is adapted to rewrite the respective node status of the third information processing apparatus storing the respective duplicate data when the original data changes; a reception unit adapted to receive a request for confirmation of the duplicated data, from the third information processing apparatus (Node C); a comparison unit adapted to compare the duplicated data which the third information processing apparatus (Node C) has received and the original data with each other, in response to the request for confirmation received by the reception unit; a registration unit adapted to register the node information indicating the third information processing apparatus, associated with the data name of the original data of the duplicated data, in the list depending on the result of comparison by the comparison unit; and a transmission unit adapted to transmit a request for a corresponding processing of the duplicated data, to the third information processing apparatus (Node C), depending on a result of the comparison by the comparison unit or the node status of the third information processing apparatus (Node C) in the list. a first storage unit adapted to store original data; a generation unit adapted to generate duplicated data of the original data; a - second storage unit adapted to store a list for managing information processing apparatuses that store duplicated data of the original data, the list including, in a manner associated with each other, data names of the original data, node information indicating the information processing apparatuses storing the respective duplicated data, and node statuses of the information processing apparatuses concerning the respective duplicated data, wherein the first information processing apparatus is adapted to rewrite the respective node status of the third information processing apparatus storing the respective duplicate data when the original data changes; a reception unit adapted to receive a request for confirmation of the duplicated data, from the third information processing apparatus (Node C); a comparison unit adapted to compare the duplicated data which the third information processing apparatus (Node C) has received and the original data with each other, in response to the request for confirmation received by the reception unit; a registration unit adapted to register the node information indicating the third information processing apparatus, associated with the data name of the original data of the duplicated data, in the list depending on the result of comparison by the comparison unit; and a transmission unit adapted to transmit a request for a corresponding processing of the duplicated data, to the third information processing apparatus (Node C), depending on a result of the comparison by the comparison unit or the node status of the third information processing apparatus (Node C) in the list.