To securely execute a designated operation command at commanded time and to facilitate the setting and the change of time and the command by executing the operation command in a storage area when designated time matches the present time.

The control part 11 of a transmission device 10 stores the commands, and supplies them to corresponding encoders 12A-12D. The respective encoders digitize video signals and sound signals from a corresponding broadcast station, compress and encode them, sequentially make them into packets at every prescribed blocks, multiplex and output them. The encoders have the storage areas of designated time and the storage areas of the commands in an RAM based on a program in an ROM. A CPU in the respective encoders sequentially read all command codes in the RAM and sequentially execute the corresponding commands when present time supplied from a time information supply source is matched with designated time in the RAM.