A transmission management system, comprising: a receiver configured to receive a communication start request that requests to start communication between a first transmission terminal and a second transmission terminal; a manager configured to manage, for each one of a plurality of transmission terminals, information regarding the time at which communication reserved for the transmission terminal is scheduled to start; an extractor configured to extract, from the manager in response to the communication start request, first time information indicating the time at which communication reserved for the first transmission terminal is scheduled to start, and second time information indicating the time at which communication reserved for the second transmission terminal is scheduled to start; a generator configured to generate reservation information regarding communication reserved for at least one of the first transmission terminal and the second transmission terminal, using the first time information and the second time information; and a transmitter configured to send the reservation information to the first transmission terminal characterized in that: the generator is further configured to generate reservation participation information indicating whether there is at least one participating terminal that is currently participating in the communication reserved for the first transmission terminal and the second transmission terminal; and the transmitter is further configured to send the reservation participation information to the first transmission terminal. a receiver configured to receive a communication start request that requests to start communication between a first transmission terminal and a second transmission terminal; a manager configured to manage, for each one of a plurality of transmission terminals, information regarding the time at which communication reserved for the transmission terminal is scheduled to start; an extractor configured to extract, from the manager in response to the communication start request, first time information indicating the time at which communication reserved for the first transmission terminal is scheduled to start, and second time information indicating the time at which communication reserved for the second transmission terminal is scheduled to start; a generator configured to generate reservation information regarding communication reserved for at least one of the first transmission terminal and the second transmission terminal, using the first time information and the second time information; and a transmitter configured to send the reservation information to the first transmission terminal characterized in that: the generator is further configured to generate reservation participation information indicating whether there is at least one participating terminal that is currently participating in the communication reserved for the first transmission terminal and the second transmission terminal; and the transmitter is further configured to send the reservation participation information to the first transmission terminal. the generator is further configured to generate reservation participation information indicating whether there is at least one participating terminal that is currently participating in the communication reserved for the first transmission terminal and the second transmission terminal; and the transmitter is further configured to send the reservation participation information to the first transmission terminal.