AN UPDATE LOG MANAGEMENT DEVICE AND AN UPDATE LOG MANAGEMENT METHOD DECREASING THE DATA AMOUNT OF TRANSMITTING AND THE UPDATE LOG AMOUNT OF HOLDING BASED ON THE RESULT OF COMPARING THE AMOUNT OF THE UPDATE LOG WITH THE AMOUNT OF THE UPDATED DATA PLUS THE LOG APPLIE

In the data sharing system which maintains the identical data among the all terminals, the update log of the updated data is deleted as early as possible. This way, the amount of data of the update logs to be recorded in a terminal can be made small. Instead of transmitting the update logs (for example, total 100 bytes) which are extracted by the extracting unit to the other terminals, an amount of data involved in transmitting is less by transmitting the data copy of the inspection data and the log applied information (for example, total 90 bytes). Because of this, the comparing unit decides that the update logs are the update logs that need not be transmitted to the other terminals. The transmitting unit transmits the data copy of the inspection data and the log applied information to the other terminals. The deleting unit decides that the update logs need not be transmitted to all the terminals, therefore, the update logs are deleted from the terminal.