Electronic data is delivered by using the secret sharing method. A transmission source device divides the electronic data into a predetermined number of partial data by using the secret sharing method and creates an arbitrary number of auxiliary data corresponding to the predetermined number of partial data and having information required for calculating the total number of the auxiliary data and the partial data. These are transmitted to a transmission destination device as a transmission destination of the electronic data via a network. The transmission destination device stores reception data containing a plurality of partial data and the auxiliary data in a storage device and restores the electronic data as the source data before the division from the partial data if the partial data and the auxiliary data has not been tampered.