In accordance with one embodiment, a digital multi-function peripheral comprises an interface, a data storage section, a memory and a processor. The interface connects an external memory device. The processor holds the authentication information of a user who connects the external memory device, generates a hash value from the information containing the authentication information of the user who connects the external memory device in a case where the state of connection of the external memory device with the interface meets a data saving condition, stores the data obtained by encrypting the data in the external memory device using the generated hash value in the data storage section, and erases the data in the external memory device.