Realizing a data communication device and a data communication method enabling to specify an IC memory mounted in the communication device and to perform data communication to the communication device in which the IC memory is mounted.A mobile device 100 of transmitting side accepts a domain ID specifying a detachable IC memory uniquely from an application 102, a communication driver 105 obtains an IP address of the device of correspondent on the basis of the accepted domain ID from a name server 300 storing the domain ID and the IP address being associated with each other. Then, the communication driver 105 obtains a port ID which an IC memory of the device of correspondent assigned to an application, and transmits the domain ID and the port ID together with a transmission data to the IP address. The device of correspondent rims the application based on the received port ID and executes an appropriate processing.