A portable terminal includes a storage device, a system unit, a signal transfer line set and a control section. The storage device stores secret data. The system unit receives the secret data from the storage unit to carry out a predetermined process associated with the secret data. The signal transfer line set is provided between the storage device and the control unit and on which a control signal and the secret data are transferred. The control signal is related to the transfer of the secret data. The control section is connected to the signal transfer line set and validates transfer of a control signal from the storage device to the system unit or from the system unit to the storage device on the signal transfer line set to permit the transfer of the secret data.