A communication message conversion device according to the present invention comprises a first receiving unit receiving a first message according to a first communication protocol, a first message storage unit storing the first message received by the first receiving unit in one of a plurality of buffer areas according to a first message identifier contained in the first message, a first identifier conversion unit converting the first message identifier contained in the first message stored in the first message storage unit into a second message identifier, a first message conversion unit packing a plurality of first messages converted with the first identifier conversion unit into a second message and a first transmission unit transmitting the second message converted with the first message conversion unit according to a second communication protocol.