To provide an inter-media synchronization system and a synchronizing method which perform data processing in time series without being affected by transmission delay on a communication network between a plurality of terminals when the terminals send data to the same terminal.

A transmitting terminal has a measuring means 1150 which measures an elapsed time, a means 1103 which stores the measured time of data transmission from the transmitting terminal to a receiving terminal, and sending-out means 1305-1307 which send data and transmission time information as one-unit information to the receiving terminal. The receiving terminal has separating means 1302A and 1302B which separate the information from the sending-out means into the data part and transmission time information, a means 1310 which stores the longest transmission time among transmission times obtained by the separating means, a means 1303 which finds differences between the longest transmission time and the respective transmission times obtained by the separating means, means 1301A and 1301B which process obtained data, and delay means 1309A and 1309B which delay the process start times of the processing means by the respective found difference times.