To transmit multiple and appropriately added data to a communication device on the receiving side, when the user of the communication device of the sending side transmit message data.

A problem is solved, by providing with a message data receiving means 121, which receives the message data from a data two-way transmission device 110 of the sending side; an external conditions acquiring means 123, which acquires information about the external conditions at the time of receiving the message data; an added data acquisition means 125, which decides and acquires the added data, which is added information from the message data received at the message data receiving means 121 and the information about the outside condition acquired at the external conditions acquiring means 123; and a message data transmitting means 126, which adds the acquired added data to the received message data and transmits it to the data two-way transmission device 110 of the receiving side.