The invention prevents data from leaking. In a data management system (1), a terminal device (2) saves a remaining data among the remaining data and an incomplete data acquired by partitioning an image data of an ID card of a user in a storage unit, and uploads the incomplete data to a data management server (5) via a network (N). A data recovery device (4) acquires the remaining data from the terminal device (2), and acquires the incomplete data from the data management server (5) via the network (N). Further, the data recovery device (4) recovers the image data of the ID card of the user from the remaining data and the incomplete data.