The present invention avoids duplication and loss of digital contents by a transmitter/receiver and a malicious third party when the digital contents are transmitted on a communication platform where direct communication is performed between IC cards. A data communications method relating to the present invention includes the steps of executing a predetermined command when an IC card 1a receives a predetermined trigger signal; storing a state of the IC card 1a before transmission of first digital contents; performing an encryption process on the first digital contents based on key information associated with the first digital contents; deleting the first digital contents from a holder 18 of the IC card 1a when a commit instruction indicating completion of a reception process on the encrypted first digital contents is received from a destination device 1b: and performing a return process to the state of the IC card 1a when a transmission process on the first digital contents is interrupted.