To provide a system of data guarantee to transmit data as necessary and to perform recovering operations in a short time while along with storing the data in a server by using a network such as the Internet and also to guarantee certainly the data with performing a recovering process in a short time while at data corruption in a system of data guarantee insurance.

In the system, when a client 4 sign-ups data guarantee insurance through a control server at an insurance company, the data is transmitted to a database center 2 from a terminal at the client 4 through the Internet to backup the data. With a configuration like that, in spite of the fact that data of the client 4 is lost due to an intrusion of a virus or a damage of a hard-disk or the like, the data can be recovered shortly.