A dynamic priority based message transmitting apparatus includes a priority storing block for recording priorities in a communication network environment having multitude nodes and recording the lowest priority among the priorities, a communication bus monitoring block for monitoring a communication bus and transmitting its message when the communication bus is available, a message collision solving block for solving message collision by monitoring message transmission when messages are transmitted from the other nodes simultaneously, comparing its priority and those of the other nodes and, as the comparison result, transmitting its message if its priority is higher than those of the other nodes while not transmitting its message if otherwise, a message filtering block for executing filtering by judging whether or not its node has to process a certain message based on an identifier of the certain message, and a priority adjusting block for adjusting its priority according to a predefined rule.