A data transfer system. The data transfer system includes a first device and a second device. The first device is configured to encrypt a partial information group of the plurality of information groups and to transfer an encrypted information group to the second device, to generate an omission information group with information having a predetermined relation omitted from at least remaining information groups of the plurality of information groups, to encrypt and to transfer the omission information group to the second device, when a partial kind of information of the plurality of information groups has the predetermined relation. The second device is configured to decrypt the partial information group and the omission information group, to restore omitted information based on the omitted information having the predetermined relation included in a transferred partial information group, and to add the restored information to the transferred omission information group.