Abstract: A message transmission/reception device preferentially processing high priority messages even in a multi-vendor environment where presence/absence of priority control function depends on each vendor. The message transmission/reception device receives, through a relay, an upstream direction message transmitted from a communication terminal to an application server, and transmits, through the relay to the communication terminal, a downstream message transmitted from the application server to the communication terminal. When receiving a high priority message, the number of messages passed by the high priority message during a period from transmitting the high priority message from the relay to receiving the high priority message is calculated. A threshold determining the amount of messages to be transmitted to the relay device is adjusted based on the calculated message number.