A packet transmission control device includes a socket detecting system that detects addresses and ports of a first device and a second device, which perform a packet communication in a network by transmitting/receiving data packets, a socket storing system that stores addresses and ports detected by the socket detecting system, a session information detecting system that detects session information regarding the packet communication according to a communication protocol of the packet communication between the first device and the second device, a session information storing system that stores the session information detected by the session information detecting system, a terminal capability detecting system that detects terminal capability of each of the first device and the second device prior to the packet communication according to the communication protocol, and a terminal capability storing system that stores the terminal capabilities detected by the terminal capability detecting system.