The present invention is to provide a data transmission device to enable a sender to easily transmit predefined data to a proper user and a proper terminal even if the receiver owns two or more user IDs and terminals. The data transmission device 100 is provided with a user icon output module 133 outputting a user icon associated with a user ID to display in a sender's terminal, and a data transmission module 136 transmitting predefined data associated with the user icon specified by a sender to a terminal corresponding to the user ID associated with the specified user icon.