The present invention relates to a message service method and a message service system. The message service method receives a message and a message transmission request from an open service application user and transmits the message to an appropriate transmission infrastructure such that the message arrives at a destination terminal. To achieve this, the message service system includes an open service application server which sends the message and the message transmission request, an open service gateway which reconstructs the message as one of a short message, a WAP Push message and a multimedia message through message analysis, and transmission infrastructures which transmits messages.