A method and system for transmitting a message to a terminal is provided, and the method for transmitting a message in a message transmission system including an Inter-Working Function (IWF) identified by a Representative Mobile Subscriber Integrated Services Digital Network Number (R-MSISDN) according to an embodiment of the present invention includes transmitting, at transmission side, a message including the R-MSISDN and an address of a recipient terminal to the IWF; extracting, at the IWF, the address of the recipient terminal from the message; acquiring, at the IWF, routing information using the address of the recipient terminal; rebuilding, at the IWF, the message using the routing information; and transmitting, at the IWF, the rebuilt message to the recipient terminal based on the routing information. The method according to an embodiment of the present invention is advantageous to transmit a message in case where the recipient routing information is not provided.