To prevent the processing sequence of messages from being reversed at the time of restarting a system after a system failure occurs.

A memory state is saved in a memory save file 9 when memory is updated. A start and end controlling part 5 restores a memory state when a system failure occurs as restoration information from the memory save file, specifies a processing message when the system failure occurs based on the restoration information and starts a message print job 7 at the time of resuming processing after the system failure occurs. A message that is acquired from the job 7 is stored as an unprocessed message in an unprocessed message file 8. When there is a notification that the message print job is over from the part 5, a message allocation controlling part 2 inputs the unprocessed message file, refers to a message allocation file 3 and instructs either of processing controlling parts 4 to process an unprocessed message.